[Darwin, PPC] Install the same headers as other sub-targets.

This is primarily in order to improve testsuite coverage, we might elect
to prune the list at some point.

2019-06-28  Iain Sandoe  <iain@sandoe.co.uk>

	* config.gcc (powerpc-*-darwin*, powerpc64-*-darwin*): Remove
	override on extra_headers.

From-SVN: r272790

gcc/ChangeLog

 2019-06-28  Iain Sandoe  <iain@sandoe.co.uk>
 
+	* config.gcc (powerpc-*-darwin*, powerpc64-*-darwin*): Remove
+	override on extra_headers.
+
+2019-06-28  Iain Sandoe  <iain@sandoe.co.uk>
+
 	* config/darwin-c.c (pop_field_alignment): Quote #pragma options.
 	* config/darwin-driver.c (darwin_default_min_version): Remove newline
 	from warning.

gcc/config.gcc

@@ -2627,13 +2627,11 @@ powerpc-*-darwin*)
 	    ;;
 	esac
 	tmake_file="${tmake_file} t-slibgcc"
-	extra_headers=altivec.h
 	;;
 powerpc64-*-darwin*)
 	extra_options="${extra_options} ${cpu_type}/darwin.opt"
 	tmake_file="${tmake_file} ${cpu_type}/t-darwin64 t-slibgcc"
 	tm_file="${tm_file} ${cpu_type}/darwin8.h ${cpu_type}/darwin64.h"
-	extra_headers=altivec.h
 	;;
 powerpc*-*-freebsd*)
 	tm_file="${tm_file} dbxelf.h elfos.h gnu-user.h ${fbsd_tm_file} rs6000/sysv4.h"