Inject default libraries to all targets in GN.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 3ed78f3baedd80413ba62b4b559db83fc09237f6..ab999379567c3130756d96387cac592a59b449e9 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -328,17 +328,6 @@ config("runtime_library") {
       "-nostdlib",
     ]
 
-    libs += [
-      # TODO(brettw) write a version of this, hopefully we can express this
-      # without forking out to GCC just to get the library name. The android
-      # toolchain directory should probably be extracted into a .gni file that
-      # this file and the android toolchain .gn file can share.
-      #   # Manually link the libgcc.a that the cross compiler uses.
-      #   '<!(<(android_toolchain)/*-gcc -print-libgcc-file-name)',
-      "c",
-      "dl",
-      "m"
-    ]
 
     # NOTE: The stlport header include paths below are specified in cflags
     # rather than include_dirs because they need to come after include_dirs.