Bug 1480631 - Copy 32-bits libraries from gcc to clang. r=froydnj

We already copy the 64-bits libraries, but don't copy the 32-bits
libraries, which prevents building for linux32 by default.

Incidentally, this also makes the clang build system build the 32-bits
compiler-rt libraries, allowing e.g. 32-bits PGO.

build/build-clang/build-clang.py

@@ -124,6 +124,9 @@ def install_libgcc(gcc_dir, clang_dir):
     libgcc_dir = os.path.join(gcc_dir, "lib64")
     clang_lib_dir = os.path.join(clang_dir, "lib")
     copy_tree(libgcc_dir, clang_lib_dir)
+    libgcc_dir = os.path.join(gcc_dir, "lib32")
+    clang_lib_dir = os.path.join(clang_dir, "lib32")
+    copy_tree(libgcc_dir, clang_lib_dir)
     include_dir = os.path.join(gcc_dir, "include")
     clang_include_dir = os.path.join(clang_dir, "include")
     copy_tree(include_dir, clang_include_dir)