Global C++11 compatibility.

Our build system compiles flex/bison as C++ rather than C, but a few
projects add `-x c` to their flags, forcing the compiler to compile
them as C. This causes the compiler to reject the global C++ standard
flag, so we need to explicitly provide a C standard flag to override
it.

Bug: 18466763
Change-Id: I49a6aeecf4abc563bd77127778b6d214e3851037
Signed-off-by: Stephen Smalley <[email protected]>

Author: DanAlbert

checkpolicy/Android.mk

@@ -23,9 +23,10 @@ common_includes := \
 	$(LOCAL_PATH)/../libsepol/src/ \
 
 ##
-# "-x c" forces the lex/yacc files to be compiled as c
-# the build system otherwise forces them to be c++
-yacc_flags := -x c
+# "-x c" forces the lex/yacc files to be compiled as c the build system
+# otherwise forces them to be c++. Need to also add an explicit -std because the
+# build system will soon default C++ to -std=c++11.
+yacc_flags := -x c -std=gnu89
 
 
 ##