Enable hardfloat CPU instructions in the FP exception handler.

This permits compiling with clang's integrated assembler.

Sponsored by:	DARPA / AFRL

sys/mips/mips/exception.S

@@ -1102,6 +1102,8 @@ END(MipsTLBMissException)
  *----------------------------------------------------------------------------
  */
 NESTED(MipsFPTrap, CALLFRAME_SIZ, ra)
+	.set push
+	.set hardfloat
 	PTR_SUBU	sp, sp, CALLFRAME_SIZ
 	mfc0	t0, MIPS_COP_0_STATUS
 	HAZARD_DELAY
@@ -1201,6 +1203,7 @@ FPReturn:
 	ITLBNOPFIX
 	j	ra
 	PTR_ADDU sp, sp, CALLFRAME_SIZ
+	.set pop
 END(MipsFPTrap)
 
 #ifndef INTRNG