Makefile.target: Allow target helpers to be in any *_helper.c file

Build all files matching *_helper.c with HELPER_CFLAGS, not just
op_helper.c. This allows you to put target helper functions which
use the global 'env' variable in multiple source files.

This only affects the ARM target as all the other targets currently only
have op_helper.c.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Makefile.target

@@ -94,7 +94,7 @@ tcg/tcg.o: cpu.h
 
 # HELPER_CFLAGS is used for all the code compiled with static register
 # variables
-op_helper.o cpu-exec.o: QEMU_CFLAGS += $(HELPER_CFLAGS)
+%_helper.o cpu-exec.o: QEMU_CFLAGS += $(HELPER_CFLAGS)
 
 # Note: this is a workaround. The real fix is to avoid compiling
 # cpu_signal_handler() in cpu-exec.c.