Fix build breakage in rs6000-aix-tdep.c

A recent change to rs6000-aix-tdep.c broke the build.  This patch
fixes it by declaring a few target descriptions in ppc-tdep.h and then
not including the various features .c files in rs6000-aix-tdep.c.


diff --git a/gdb/ppc-tdep.h b/gdb/ppc-tdep.h
index fe41bae..db4e532 100644
--- a/gdb/ppc-tdep.h
+++ b/gdb/ppc-tdep.h
@@ -450,4 +450,10 @@ struct ppc_inferior_data
 
 extern ppc_inferior_data * get_ppc_per_inferior (inferior *inf);
 
+extern const struct target_desc *tdesc_powerpc_vsx64l;
+extern const struct target_desc *tdesc_powerpc_vsx64;
+extern const struct target_desc *tdesc_powerpc_vsx32;
+extern const struct target_desc *tdesc_powerpc_altivec64;
+extern const struct target_desc *tdesc_powerpc_altivec32;
+
 #endif /* ppc-tdep.h */
diff --git a/gdb/rs6000-aix-tdep.c b/gdb/rs6000-aix-tdep.c
index c56e5a3..d4a7b22 100644
--- a/gdb/rs6000-aix-tdep.c
+++ b/gdb/rs6000-aix-tdep.c
@@ -40,11 +40,6 @@
 #include "trad-frame.h"
 #include "frame-unwind.h"
 
-#include "features/rs6000/powerpc-altivec32.c"
-#include "features/rs6000/powerpc-vsx32.c"
-#include "features/rs6000/powerpc-altivec64.c"
-#include "features/rs6000/powerpc-vsx64.c"
-
 /* If the kernel has to deliver a signal, it pushes a sigcontext
    structure on the stack and then calls the signal handler, passing
    the address of the sigcontext in an argument register.  Usually