8288719: [arm32] SafeFetch32 thumb interleaving causes random crashes

8284997: arm32 build crashes since JDK-8283326

Reviewed-by: snazarki, xliu, lucy

Author: tstuefe

src/hotspot/os_cpu/linux_arm/safefetch_linux_arm.S

@@ -26,6 +26,7 @@
     .globl SafeFetch32_impl
     .globl _SafeFetch32_fault
     .globl _SafeFetch32_continuation
+    .type SafeFetch32_impl, %function
 
     # Support for int SafeFetch32(int* address, int defaultval);
     #

src/hotspot/share/runtime/safefetch.hpp

@@ -34,11 +34,10 @@
 #ifdef _WIN32
   // Windows uses Structured Exception Handling
   #include "safefetch_windows.hpp"
-#elif defined(ZERO) || defined (_AIX) || defined (ARM32)
+#elif defined(ZERO) || defined (_AIX)
   // These platforms implement safefetch via Posix sigsetjmp/longjmp.
   // This is slower than the other methods and uses more thread stack,
   // but its safe and portable.
-  // (arm32 uses sigsetjmp/longjmp as long as JDK-8284997 is not solved)
   #include "safefetch_sigjmp.hpp"
   #define SAFEFETCH_METHOD_SIGSETJMP
 #else