[PATCH, committed] Update t-rs6000 for automatic dependencies

[David Edelsohn]

All of the rs6000-specific dependencies are included and discovered
automatically.

Bootstrapped on powerpc-ibm-aix7.1.0.0.

David

        * config/rs6000/t-rs6000 (rs6000.o): Remove.
        (rs6000-c.o): Use COMPILE and POSTCOMPILE.

Index: config/rs6000/t-rs6000
===================================================================
--- config/rs6000/t-rs6000      (revision 202942)
+++ config/rs6000/t-rs6000      (working copy)
@@ -20,22 +20,10 @@

 TM_H += $(srcdir)/config/rs6000/rs6000-builtin.def

-rs6000.o: $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
-  $(RTL_H) $(REGS_H) hard-reg-set.h \
-  real.h insn-config.h conditions.h insn-attr.h flags.h $(RECOG_H) \
-  $(OBSTACK_H) $(TREE_H) $(EXPR_H) $(OPTABS_H) except.h function.h \
-  output.h dbxout.h $(BASIC_BLOCK_H) toplev.h $(GGC_H) $(HASHTAB_H) \
-  $(TM_P_H) $(TARGET_H) $(TARGET_DEF_H) langhooks.h reload.h gt-rs6000.h \
-  cfgloop.h $(OPTS_H) $(COMMON_TARGET_H) dumpfile.h \
-  $(srcdir)/config/rs6000/rs6000-cpus.def
+rs6000-c.o: $(srcdir)/config/rs6000/rs6000-c.c
+       $(COMPILE) $<
+       $(POSTCOMPILE)

-rs6000-c.o: $(srcdir)/config/rs6000/rs6000-c.c \
-    $(srcdir)/config/rs6000/rs6000-protos.h \
-    $(CONFIG_H) $(SYSTEM_H) $(TREE_H) $(CPPLIB_H) \
-    $(TM_P_H) $(C_PRAGMA_H) errors.h coretypes.h $(TM_H)
-       $(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
-               $(srcdir)/config/rs6000/rs6000-c.c
-
 $(srcdir)/config/rs6000/rs6000-tables.opt: $(srcdir)/config/rs6000/genopt.sh \
   $(srcdir)/config/rs6000/rs6000-cpus.def
        $(SHELL) $(srcdir)/config/rs6000/genopt.sh $(srcdir)/config/rs6000 > \