Change Perfetto Source to Github (#373)

- Current Perfetto source repo is from android.googlesource
        which is censored in China and causes an infinite
        hang when building Omnitrace
- This commit changes the Perfetto source repo to Github which acts
        as a read-only mirror to the googlesource perfetto
        repo.

Co-authored-by: David Galiffi <David.Galiffi@amd.com>

[ROCm/rocprofiler-systems commit: 6f22b2d2e5]

projects/rocprofiler-systems/cmake/Packages.cmake

@@ -482,7 +482,7 @@ set(perfetto_DIR ${PROJECT_SOURCE_DIR}/external/perfetto)
 omnitrace_checkout_git_submodule(
     RELATIVE_PATH external/perfetto
     WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-    REPO_URL https://android.googlesource.com/platform/external/perfetto
+    REPO_URL https://github.com/google/perfetto.git
     REPO_BRANCH v46.0
     TEST_FILE sdk/perfetto.cc)