cdefs.h: add artificial attribute to FORTIFY_SOURCE functions

Otherwise the gcc compiler warning doesn't show up.

Add -Wno-error to fortify related tests. Fortify related tests
are expected to be examples of bad programs, and in many
cases shouldn't compile cleanly. Rewriting them to compile
cleanly isn't feasible nor desirable.

Bug: 17784968
Change-Id: I93bececa7444d965f18c7c27d46e7abce5c49a02

libc/include/sys/cdefs.h

@@ -53,6 +53,9 @@
 #ifndef __has_builtin
 #define __has_builtin(x)        0
 #endif
+#ifndef __has_attribute
+#define __has_attribute(x)      0
+#endif
 
 
 /*
@@ -534,8 +537,12 @@
 #endif
 #define __bos0(s) __builtin_object_size((s), 0)
 
+#if __GNUC_PREREQ(4,3) || __has_attribute(__artificial__)
+#define __BIONIC_FORTIFY_INLINE extern __inline__ __always_inline __attribute__((gnu_inline)) __attribute__((__artificial__))
+#else
 #define __BIONIC_FORTIFY_INLINE extern __inline__ __always_inline __attribute__((gnu_inline))
 #endif
+#endif
 #define __BIONIC_FORTIFY_UNKNOWN_SIZE ((size_t) -1)
 
 /* Used to tag non-static symbols that are private and never exposed by the shared library. */

tests/Android.mk

@@ -152,11 +152,10 @@ $(foreach compiler,gcc clang, \
   $(foreach test,1 2, \
     $(eval fortify$(test)-tests-$(compiler)_cflags := \
       $(test_cflags) \
+      -Wno-error \
       -U_FORTIFY_SOURCE \
       -D_FORTIFY_SOURCE=$(test) \
       -DTEST_NAME=Fortify$(test)_$(compiler)); \
-    $(eval fortify$(test)-tests-$(compiler)_cflags_host := \
-      -Wno-error); \
     $(eval fortify$(test)-tests-$(compiler)_src_files := \
       fortify_test.cpp); \
     $(eval fortify_libs += fortify$(test)-tests-$(compiler)); \