Toolchain: Move GDB build to a separate script

Target GDB is only used for debugging the kernel, which is not relevant
to most people. Starting with 924758c6f8, GDB would always be built
as part of the toolchain if the user didn't have it installed. This is
unnecessary.

This commit adds a separate script for building GDB, which the user
needs to explicitly invoke. A message is added to Meta/debug-kernel.sh
which alerts the user to this fact.

Toolchain/BuildIt.sh

@@ -80,12 +80,6 @@ BINUTILS_NAME="binutils-$BINUTILS_VERSION"
 BINUTILS_PKG="${BINUTILS_NAME}.tar.gz"
 BINUTILS_BASE_URL="https://ftp.gnu.org/gnu/binutils"
 
-GDB_VERSION="13.1"
-GDB_MD5SUM="92b70971e81a450f6b3e1cf568671cfa"
-GDB_NAME="gdb-$GDB_VERSION"
-GDB_PKG="${GDB_NAME}.tar.gz"
-GDB_BASE_URL="https://ftp.gnu.org/gnu/gdb"
-
 # Note: If you bump the gcc version, you also have to update the matching
 #       GCC_VERSION variable in the project's root CMakeLists.txt
 GCC_VERSION="12.2.0"
@@ -100,21 +94,6 @@ buildstep() {
     "$@" 2>&1 | sed $'s|^|\x1b[34m['"${NAME}"$']\x1b[39m |'
 }
 
-has_gdb() {
-    ARCH=$1
-    ARCH_DASH="${ARCH//_/-}"
-    if command -v gdb >/dev/null && gdb -ex 'set architecture' -ex 'quit' 2>&1 | grep "$ARCH_DASH"; then
-        return 0
-    else
-        command -v "$ARCH"-elf-gdb >/dev/null
-    fi
-}
-
-NEEDS_GDB=1
-if has_gdb "$ARCH"; then
-    NEEDS_GDB=0
-fi
-
 # === DEPENDENCIES ===
 buildstep dependencies echo "Checking whether 'make' is available..."
 if ! command -v ${MAKE:-make} >/dev/null; then
@@ -197,22 +176,6 @@ popd
 # === DOWNLOAD AND PATCH ===
 
 pushd "$DIR/Tarballs"
-    # Build gdb for cross-debugging support
-    if [ $NEEDS_GDB -eq 1 ]; then
-        echo "GDB not found for $ARCH. Will build it from source."
-        md5=""
-        if [ -e "$GDB_PKG" ]; then
-            md5="$($MD5SUM $GDB_PKG | cut -f1 -d' ')"
-            echo "gdb md5='$md5'"
-        fi
-        if [ "$md5" != ${GDB_MD5SUM} ] ; then
-            rm -f $GDB_PKG
-            curl -LO "$GDB_BASE_URL/$GDB_PKG"
-        else
-            echo "Skipped downloading gdb"
-        fi
-    fi
-
     md5=""
     if [ -e "$BINUTILS_PKG" ]; then
         md5="$($MD5SUM $BINUTILS_PKG | cut -f1 -d' ')"
@@ -237,29 +200,6 @@ pushd "$DIR/Tarballs"
         echo "Skipped downloading gcc"
     fi
 
-    if [ $NEEDS_GDB -eq 1 ]; then
-        if [ -d ${GDB_NAME} ]; then
-            rm -rf "${GDB_NAME}"
-            rm -rf "$DIR/Build/$ARCH/$GDB_NAME"
-        fi
-        echo "Extracting GDB..."
-        tar -xzf ${GDB_PKG}
-
-        pushd ${GDB_NAME}
-            if [ "$git_patch" = "1" ]; then
-                git init > /dev/null
-                git add . > /dev/null
-                git commit -am "BASE" > /dev/null
-                git am "${DIR}"/Patches/gdb/*.patch > /dev/null
-            else
-                for patch in "${DIR}"/Patches/gdb/*.patch; do
-                    patch -p1 < "${patch}" > /dev/null
-                done
-            fi
-            $MD5SUM "$DIR"/Patches/gdb/*.patch > .patch.applied
-        popd
-    fi
-
     patch_md5="$(${MD5SUM} "${DIR}"/Patches/binutils/*.patch)"
 
     if [ ! -d "${BINUTILS_NAME}" ] || [ "$(cat ${BINUTILS_NAME}/.patch.applied)" != "${patch_md5}" ]; then
@@ -335,43 +275,6 @@ mkdir -p "$DIR/Build/$ARCH"
 pushd "$DIR/Build/$ARCH"
     unset PKG_CONFIG_LIBDIR # Just in case
 
-    if [ $NEEDS_GDB -eq 1 ]; then
-        rm -rf gdb
-        mkdir -p gdb
-
-        pushd gdb
-            echo "XXX configure gdb"
-
-
-            if [ "$SYSTEM_NAME" = "Darwin" ]; then
-                buildstep "gdb/configure" "$DIR"/Tarballs/$GDB_NAME/configure --prefix="$PREFIX" \
-                                                        --target="$TARGET" \
-                                                        --with-sysroot="$SYSROOT" \
-                                                        --enable-shared \
-                                                        --disable-werror \
-                                                        --with-libgmp-prefix="$(brew --prefix gmp)" \
-                                                        --with-gmp="$(brew --prefix gmp)" \
-                                                        --with-isl="$(brew --prefix isl)" \
-                                                        --with-mpc="$(brew --prefix libmpc)" \
-                                                        --with-mpfr="$(brew --prefix mpfr)" \
-                                                        --disable-nls \
-                                                        ${TRY_USE_LOCAL_TOOLCHAIN:+"--quiet"} || exit 1
-            else
-                buildstep "gdb/configure" "$DIR"/Tarballs/$GDB_NAME/configure --prefix="$PREFIX" \
-                                                        --target="$TARGET" \
-                                                        --with-sysroot="$SYSROOT" \
-                                                        --enable-shared \
-                                                        --disable-werror \
-                                                        --disable-nls \
-                                                        ${TRY_USE_LOCAL_TOOLCHAIN:+"--quiet"} || exit 1
-            fi
-
-            echo "XXX build gdb"
-            buildstep "gdb/build" "$MAKE" MAKEINFO=true -j "$MAKEJOBS" || exit 1
-            buildstep "gdb/install" "$MAKE" MAKEINFO=true install || exit 1
-        popd
-    fi
-
     rm -rf binutils
     mkdir -p binutils