Use $ORIGIN/../lib64 as rpath for Rust binaries

Note that we still need to use the clang-r* path too here because of how
tablegen and other tools get used in Rust's build.

Bug: http://b/186438813
Test: ./build.py and inspect RUNPATH via llvm-readelf
Change-Id: I21880e8cea9b8703fb10889781aa7cb05fd344b1

Author: stephenhines

build.py

@@ -167,6 +167,17 @@ def main():
         paths.out_path('bin', 'cargo'),
         paths.out_path('bin', 'rustdoc')])
 
+    # Install the libc++ library to lib64/
+    if build_platform.system() == 'darwin':
+        libcxx_name = 'libc++.dylib'
+    else:
+        libcxx_name = 'libc++.so'
+    lib64_path = paths.out_path('lib64')
+    if not os.path.exists(lib64_path):
+        os.makedirs(lib64_path)
+    shutil.copy2(paths.cxx_linker_path(libcxx_name),
+                 paths.out_path('lib64', libcxx_name))
+
     # Some stdlib crates might include Android.mk or Android.bp files.
     # If they do, filter them out.
     if build_platform.system() == 'linux':

config_toml.py

@@ -36,15 +36,14 @@ def configure():
         ar = paths.llvm_prebuilt('bin', 'llvm-ar')
         cxxstd = paths.llvm_prebuilt('include', 'c++', 'v1')
         ranlib = paths.llvm_prebuilt('bin', 'llvm-ranlib')
-        # Add the path at which libc++ can be found during the build
-        cxx_linker_flags = ' -Wl,-rpath,' + paths.cxx_linker_path()
         # Add the path at which libc++ can be found in Android checkouts
-        cxx_linker_flags += ' -Wl,-rpath,'
+        cxx_linker_flags = ' -Wl,-rpath,'
         if build_platform.system() == 'darwin':
-            cxx_linker_flags += '@loader_path/'
+            cxx_linker_flags += '@loader_path/../lib64'
         else:
-            cxx_linker_flags += '\\$ORIGIN/'
-        cxx_linker_flags += paths.android_cxx_linker_path()
+            cxx_linker_flags += '\\$ORIGIN/../lib64'
+        # Add the path at which libc++ can be found during the build
+        cxx_linker_flags += ' -Wl,-rpath,' + paths.cxx_linker_path()
 
         def host_config(target):
             wrapper_name = paths.this_path('clang-%s' % target)