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: Id68ad9317261ed4d857a949b07288bd137ff6303

edify/Android.mk

@@ -7,9 +7,10 @@ edify_src_files := \
 	parser.y \
 	expr.c
 
-# "-x c" forces the lex/yacc files to be compiled as c;
-# the build system otherwise forces them to be c++.
-edify_cflags := -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.
+edify_cflags := -x c -std=gnu89
 
 #
 # Build the host-side command line tool