[Support] Fix `-ftime-trace-granularity` option

Summary:
Move `-ftime-trace-granularity` option to frontend options. Without patch
this option is showed up in the help for any tool that links libSupport.

Reviewers: sammccall

Subscribers: hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D65202

llvm-svn: 366911
diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index 4c1fe07..aa53782 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -1944,6 +1944,14 @@
 
 .. option:: -ftime-report
 
+.. option:: -ftime-trace
+
+Turn on time profiler
+
+.. option:: -ftime-trace-granularity=<arg>
+
+Minimum time granularity (in microseconds) traced by time profiler
+
 .. option:: -ftls-model=<arg>
 
 .. option:: -ftrap-function=<arg>