Toolchain+Ports: Update LLVM to 14.0.1

Besides a version bump, the following changes have been made to our
toolchain infrastructure:
- LLVM/Clang is now built with -march=native if the host compiler
  supports it. An exception to this is CI, as the toolchain cache is
  shared among many different machines there.
- The LLVM tarball is not re-extracted if the hash of the applied
  patches doesn't differ.
- The patches have been split up into atomic chunks.
- Port-specific patches have been integrated into the main patches,
  which will aid in the work towards self-hosting.
- <sysroot>/usr/local/lib is now appended to the linker's search path by
  default.
- --pack-dyn-relocs=relr is appended to the linker command line by
  default, meaning ports take advantage of RELR relocations without any
  patches or additional compiler flags.

The formatting of LLVM port's package.sh has been bothering me, so I
also indented the arguments to the CMake invocation.

Toolchain/Patches/llvm/ReadMe.md

@@ -0,0 +1,78 @@
+# Patches for llvm on SerenityOS
+
+## `0001-Support-Add-support-for-building-LLVM-on-SerenityOS.patch`
+
+Add support for building LLVM on SerenityOS
+
+Adds SerenityOS `#ifdef`s for platform-specific code.
+
+We stub out wait4, as SerenityOS doesn't support querying a child
+process's resource usage information.
+
+## `0002-Triple-Add-triple-for-SerenityOS.patch`
+
+Add triple for SerenityOS
+
+
+## `0003-Driver-Add-support-for-SerenityOS.patch`
+
+Add support for SerenityOS
+
+Adds support for the `$arch-pc-serenity` target to the Clang front end.
+This makes the compiler look for libraries and headers in the right
+places, and enables some security mitigations like stack-smashing
+protection and position-independent code by default.
+
+## `0004-Driver-Default-to-ftls-model-initial-exec-on-Serenit.patch`
+
+Default to -ftls-model=initial-exec on SerenityOS
+
+This is a hack to make Clang use the initial-exec TLS model instead of
+the default local-exec when building code for Serenity.
+
+This patch should be removed when we implement proper TLS support.
+
+## `0005-libc-Add-support-for-SerenityOS.patch`
+
+Add support for SerenityOS
+
+This commit teaches libc++ about what features are available in our
+LibC, namely:
+* We do not have locale support, so no-op shims should be used in place
+  of the C locale API.
+* The number of errno constants defined by us is given by the value of
+  the `ELAST` macro.
+* Multithreading is implemented though the pthread library.
+* Aligned memory allocation is provided by the MSVCRT-like
+  `_aligned_{malloc,free}` functions.
+
+Adds a hack for a header not found error when including
+`<initializer_list>` inside the SerenityOS kernel.
+
+Makes libc++ use its builtin character type table instead of the one
+provided by LibC as it is incomplete.
+
+## `0006-compiler-rt-Build-crtbegin.o-crtend.o-for-SerenityOS.patch`
+
+Build crtbegin.o/crtend.o for SerenityOS
+
+
+## `0007-cmake-Allow-undefined-symbols-on-SerenityOS.patch`
+
+Allow undefined symbols on SerenityOS
+
+Allow undefined symbols in LLVM libraries, which is needed because only
+stubs are available for SerenityOS libraries when libc++ and libunwind
+are built.
+
+## `0008-cmake-Support-building-shared-libLLVM-and-libClang-f.patch`
+
+Support building shared libLLVM and libClang for SerenityOS
+
+This patch tells CMake that the --whole-archive linker option should be
+used for specifying the archives whose members will constitute these
+shared libraries.
+
+Symbol versioning is disabled, as the SerenityOS loader doesn't support
+it, and the ELF sections that store version data would just waste space.
+