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

(cherry picked from commit 1aaa17802c92d99ae170245c2b2f15a6c27b133e)

Change-Id: Ib6df1a3f44b55b1fff222e78395c10c51cd39817
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index c764e9b..504e439 100644
--- a/libc/include/sys/cdefs.h
+++ b/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
 
 
 /*
@@ -511,8 +514,12 @@
 #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. */
diff --git a/tests/Android.mk b/tests/Android.mk
index 69ff811..dd43049 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -171,11 +171,10 @@
   $(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)); \