Update compile_db.py for Windows.

'tools\clang\pylib\clang\compile_db.py' uses 'ninja' file to run ninja,
while on windows 'ninja.exe' should be called.

Change-Id: I2431aeb8b4c887acf0b8a0d8cafac83d062bda78
Reviewed-on: https://chromium-review.googlesource.com/894206Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533595}

tools/clang/pylib/clang/compile_db.py

@@ -72,9 +72,10 @@ def _ProcessCompileDatabaseForWindows(compile_db):
 
 
 def GetNinjaPath():
+  ninja_executable = 'ninja.exe' if sys.platform == 'win32' else 'ninja'
   return os.path.join(
       os.path.dirname(os.path.realpath(__file__)),
-        '..', '..', '..', '..', 'third_party', 'depot_tools', 'ninja')
+        '..', '..', '..', '..', 'third_party', 'depot_tools', ninja_executable)
 
 
 # FIXME: This really should be a build target, rather than generated at runtime.