Switch .eh_frame to readonly (from "aw" to "a").

external/libffi/src/x86/sysv.S:832:1: error: changed section flags for .eh_frame, expected: 0x2
.section .eh_frame,"aw",@progbits
^

Bug: http://b/155835175
Test: mma in external/libffi for an x86 target
Change-Id: I5cd91db87461fd74aa473e38d1682c190d75bc2b

Author: stephenhines

linux-x86/fficonfig.h

@@ -9,7 +9,7 @@
 #undef C_ALLOCA
 
 /* Define to the flags needed for the .section .eh_frame directive. */
-#define EH_FRAME_FLAGS "aw"
+#define EH_FRAME_FLAGS "a"
 
 /* Define this if you want extra debugging. */
 #undef FFI_DEBUG
@@ -68,7 +68,7 @@
 #define HAVE_MMAP_FILE 1
 
 /* Define if .eh_frame sections should be read-only. */
-#undef HAVE_RO_EH_FRAME
+#define HAVE_RO_EH_FRAME 1
 
 /* Define to 1 if you have the <stdint.h> header file. */
 #define HAVE_STDINT_H 1