Fix the preprocessor statements controlling the use of mips{32,64}r1 instructions.

Only enable code using mips32/mips64 instructions if the compiler is targetting
this ISA. (integer madd and msub instructions aren't available in the
``canonical'' mips ISAs)

libFDK/include/mips/cplx_mul.h

@@ -89,7 +89,7 @@ amm-info@iis.fraunhofer.de
 ******************************************************************************/
 
 
-#if defined(__GNUC__) && defined(__mips__) && __mips_isa_rev < 6
+#if defined(__GNUC__) && defined(__mips_isa_rev) && __mips_isa_rev < 6
 
 
 //#define FUNCTION_cplxMultDiv2_32x16