Declutter rpath.

Before:
$ ldd out/Release chrome
...
libbase.so =>
/usr/local/google/home/yangguo/chromium/src/out/Release/./libbase.so
(0x00007fee94d8d000)
...
libmidi.so =>
/usr/local/google/home/yangguo/chromium/src/out/Release/././libmidi.so
(0x00007fee86d12000) ...

After:
...
libbase.so =>
/usr/local/google/home/yangguo/chromium/src/out/Release/libbase.so
(0x00007fee94d8d000)
...
libmidi.so =>
/usr/local/google/home/yangguo/chromium/src/out/Release/libmidi.so
(0x00007fee86d12000)
...
Change-Id: I25b281e8f26ac84848a33e4107e22b4abeca3c7e

R=thakis@chromium.org

Change-Id: I25b281e8f26ac84848a33e4107e22b4abeca3c7e
Reviewed-on: https://chromium-review.googlesource.com/c/1458183
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631602}

build/config/gcc/BUILD.gn

@@ -68,7 +68,7 @@ config("rpath_for_built_shared_libraries") {
     if (current_toolchain != default_toolchain || gcc_target_rpath == "") {
       ldflags = [
         # Want to pass "\$". GN will re-escape as required for ninja.
-        "-Wl,-rpath=\$ORIGIN/.",
+        "-Wl,-rpath=\$ORIGIN",
       ]
     } else {
       ldflags = [ "-Wl,-rpath=${gcc_target_rpath}" ]