rs6000: clean up testsuite power10_hw check

Because the check for power10_hw is not called
check_effective_target_power10_hw, it needs to be looked
for by is-effective-target-keyword. Also reorder things
in is-effective-target to put power10_hw with the other
ppc stuff.

2020-07-13  Aaron Sawdey  <acsawdey@linux.ibm.com>

gcc/testsuite/

	* lib/target-supports.exp (is-effective-target):
	Reorder to put powerpc stuff together.
	(is-effective-target-keyword): Add power10_hw.

(cherry picked from commit 94c7c67b82dd7255fde0d7ae42d483336ea1b60b)

gcc/testsuite/lib/target-supports.exp

@@ -7824,6 +7824,7 @@ proc is-effective-target { arg } {
 	  "p8vector_hw"    { set selected [check_p8vector_hw_available] }
 	  "p9vector_hw"    { set selected [check_p9vector_hw_available] }
 	  "p9modulo_hw"    { set selected [check_p9modulo_hw_available] }
+	  "power10_hw"     { set selected [check_power10_hw_available] }
 	  "ppc_float128_sw" { set selected [check_ppc_float128_sw_available] }
 	  "ppc_float128_hw" { set selected [check_ppc_float128_hw_available] }
 	  "ppc_recip_hw"   { set selected [check_ppc_recip_hw_available] }
@@ -7834,7 +7835,6 @@ proc is-effective-target { arg } {
 	  "named_sections" { set selected [check_named_sections_available] }
 	  "gc_sections"    { set selected [check_gc_sections_available] }
 	  "cxa_atexit"     { set selected [check_cxa_atexit_available] }
-	  "power10_hw" { set selected [check_power10_hw_available] }
 	  default          { error "unknown effective target keyword `$arg'" }
 	}
     }
@@ -7856,6 +7856,7 @@ proc is-effective-target-keyword { arg } {
 	  "p8vector_hw"    { return 1 }
 	  "p9vector_hw"    { return 1 }
 	  "p9modulo_hw"    { return 1 }
+	  "power10_hw"     { return 1 }
 	  "ppc_float128_sw" { return 1 }
 	  "ppc_float128_hw" { return 1 }
 	  "ppc_recip_hw"   { return 1 }