Pass NO_MISSING_FIELD_INITIALIZERS to Compiler Flags

configure checks whether -Wno-missing-field-initializers is a valid
compiler flag but it was never actually used in Makefile.rules.
Enable it to avoid some ridiculous warnings from gcc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172870 91177308-0d34-0410-b5e6-96231b3b80d8

Makefile.rules

@@ -669,7 +669,8 @@ CompileCommonOpts += -pedantic -Wno-long-long
 endif
 CompileCommonOpts += -Wall -W -Wno-unused-parameter -Wwrite-strings \
                      $(EXTRA_OPTIONS) $(COVERED_SWITCH_DEFAULT) \
-                     $(NO_UNINITIALIZED) $(NO_MAYBE_UNINITIALIZED)
+                     $(NO_UNINITIALIZED) $(NO_MAYBE_UNINITIALIZED) \
+                     $(NO_MISSING_FIELD_INITIALIZERS)
 # Enable cast-qual for C++; the workaround is to use const_cast.
 CXX.Flags += -Wcast-qual