or1k: Do not clear existing FPU exceptions before updating

We should always carry the exceptions forward.  This bug was found when
working on testing glibc math tests, many tests were failing with
Overflow and Underflow flags not set.  This was traced to here.

libgcc/ChangeLog:

	* config/or1k/sfp-machine.h (FP_HANDLE_EXCEPTIONS): Remove
	statement clearing existing exceptions.

libgcc/config/or1k/sfp-machine.h

@@ -73,7 +73,6 @@ do {								\
 do {								\
   if (__builtin_expect (_fex, 0))				\
     {								\
-      _fpcsr &= ~FP_EX_ALL;					\
       _fpcsr |= _fex;						\
       __asm__ volatile ("l.mtspr r0,%0,20" : : "r" (_fpcsr));	\
     }								\