[arm] Add missing Makefile dependency on arm_acle_builtins.def

arm-builtins.o is missing a Makefile dependency on arm_acle_builtins.def
which can cause inconsistent rebuilds
when adding builtins in there.

This patch adds the right Makefile-foo to fix that.

	* config/arm/t-arm (arm-builtins.o): Add dependency on
	arm_acle_builtins.def.

From-SVN: r276057

gcc/ChangeLog

+2019-09-23  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* config/arm/t-arm (arm-builtins.o): Add dependency on
+	arm_acle_builtins.def.
+
 2019-09-23  Richard Sandiford  <richard.sandiford@arm.com>
 
 	PR target/91823

gcc/config/arm/t-arm

@@ -141,6 +141,7 @@ arm-builtins.o: $(srcdir)/config/arm/arm-builtins.c $(CONFIG_H) \
   $(RTL_H) $(TREE_H) expr.h $(TM_P_H) $(RECOG_H) langhooks.h \
   $(DIAGNOSTIC_CORE_H) $(OPTABS_H) \
   $(srcdir)/config/arm/arm-protos.h \
+  $(srcdir)/config/arm/arm_acle_builtins.def \
   $(srcdir)/config/arm/arm_neon_builtins.def \
   $(srcdir)/config/arm/arm_vfp_builtins.def \
   $(srcdir)/config/arm/arm-simd-builtin-types.def