Toolchain: Use curl instead of wget (#2574)

- For Linux: curl is already listed as a dependency;
- For macOS: curl is pre-installed;
- For OpenBSD and FreeBSD: curl is a dependecy of git.

Toolchain/BuildIt.sh

@@ -117,7 +117,7 @@ pushd "$DIR/Tarballs"
     echo "bu md5='$md5'"
     if [ ! -e $BINUTILS_PKG ] || [ "$md5" != ${BINUTILS_MD5SUM} ] ; then
         rm -f $BINUTILS_PKG
-        wget "$BINUTILS_BASE_URL/$BINUTILS_PKG"
+        curl -LO "$BINUTILS_BASE_URL/$BINUTILS_PKG"
     else
         echo "Skipped downloading binutils"
     fi
@@ -126,7 +126,7 @@ pushd "$DIR/Tarballs"
     echo "gc md5='$md5'"
     if [ ! -e $GCC_PKG ] || [ "$md5" != ${GCC_MD5SUM} ] ; then
         rm -f $GCC_PKG
-        wget "$GCC_BASE_URL/$GCC_NAME/$GCC_PKG"
+        curl -LO "$GCC_BASE_URL/$GCC_NAME/$GCC_PKG"
     else
         echo "Skipped downloading gcc"
     fi