Bug 1719225 - Don't build binutils as part of gcc. r=firefox-build-system-reviewers,andi

We have a separate binutils toolchain already, and the only remaining
use of the binutils part of the the GCC toolchain is for the gold plugin
headers for clang, which we can add to the toolchain sysroot.

Differential Revision: https://phabricator.services.mozilla.com/D119133

build/build-clang/build-clang.py

@@ -169,19 +169,6 @@ def delete(path):
 def install_libgcc(gcc_dir, clang_dir, is_final_stage):
     gcc_bin_dir = os.path.join(gcc_dir, "bin")
 
-    # Copy over gcc toolchain bits that clang looks for, to ensure that
-    # clang is using a consistent version of ld, since the system ld may
-    # be incompatible with the output clang produces.  But copy it to a
-    # target-specific directory so a cross-compiler to Mac doesn't pick
-    # up the (Linux-specific) ld with disastrous results.
-    #
-    # Only install this for the bootstrap process; we expect any consumers of
-    # the newly-built toolchain to provide an appropriate ld themselves.
-    if not is_final_stage:
-        x64_bin_dir = os.path.join(clang_dir, "x86_64-unknown-linux-gnu", "bin")
-        mkdir_p(x64_bin_dir)
-        shutil.copy2(os.path.join(gcc_bin_dir, "ld"), x64_bin_dir)
-
     out = subprocess.check_output(
         [os.path.join(gcc_bin_dir, "gcc"), "-print-libgcc-file-name"]
     )
@@ -321,7 +308,7 @@ def build_one_stage(
         if build_wasm:
             cmake_args += ["-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly"]
         if is_linux():
-            cmake_args += ["-DLLVM_BINUTILS_INCDIR=%s/include" % gcc_dir]
+            cmake_args += ["-DLLVM_BINUTILS_INCDIR=/usr/include"]
             cmake_args += ["-DLLVM_ENABLE_LIBXML2=FORCE_ON"]
             sysroot = os.path.join(os.environ.get("MOZ_FETCHES_DIR", ""), "sysroot")
             if os.path.exists(sysroot):