libdfp: Fixes for isinfd

This patch has three changes:
1. isinfd[32|64|128] now return -1 for minux infinity
2. powerpc isinf128d now uses the isinf32.d template instead of the
   is_template.h
3. powerpc isinf32d  was simplified to check the cr0 value in C
   instead of assembly tests.
libdfp: Fixes for isfinited

This patches makes PowerPC HW DFP code return a positive integer as
other implementations. It also simplifies the is_template.h implementation
by chekcing cr0 result in C instead of assembly.
libdfp: Fix issues with getexp when exp is DECIMAL_BIAS
Fix ChangeLg format