--- a/src/gcc/config/arm/arm.h	2017-09-09 18:34:30.000000000 +0200
+++ b/src/gcc/config/arm/arm.h	2018-08-28 12:37:44.893553053 +0200
@@ -2315,4 +2315,7 @@
    representation for SHF_ARM_PURECODE in GCC.  */
 #define SECTION_ARM_PURECODE SECTION_MACH_DEP
 
+#undef  NO_IMPLICIT_EXTERN_C
+#define NO_IMPLICIT_EXTERN_C 1
+
 #endif /* ! GCC_ARM_H */