mips.exp: Redefine isa variable which is referenced in later code.

gcc/testsuite/
	* gcc.target/mips/mips.exp (mips-dg-options): Redefine isa
	which is used in later code.

From-SVN: r226957

gcc/testsuite/ChangeLog

+2015-08-17  Matthew Fortune  <matthew.fortune@imgtec.com>
+
+	* gcc.target/mips/mips.exp (mips-dg-options): Redefine isa
+	which is used in later code.
+
 2015-08-17  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/67216

gcc/testsuite/gcc.target/mips/mips.exp

@@ -1190,6 +1190,7 @@ proc mips-dg-options { args } {
 
     # Re-calculate the isa_rev for use in the abi handling code below
     set arch [mips_option options arch]
+    set isa [mips_arch_info $arch isa]
     set isa_rev [mips_arch_info $arch isa_rev]
 
     # Set an appropriate ABI, handling dependencies between the pre-abi