Mostly fix Sun Studio configuration using SunCC compiler

The SunCC compiler in Sun Studio 12.5 crashes on the m4 macro test test_type_deduction (line 257). The Sun Studio 12.6 compiler finishes configuring.

m4/acx_check_suncc.m4

@@ -26,7 +26,7 @@ AC_DEFUN([ACX_CHECK_SUNCC],[
   AS_IF([test "$SUNCC" = "yes" -a "x${ac_cv_env_CXXFLAGS_set}" = "x"],[
     dnl Sun Studio has a crashing bug with -xO4 in some cases. Keep this
     dnl at -xO3 until a proper test to detect those crashes can be done.
-    CXXFLAGS="-g0 -xO3 -xlibmil -xdepend -xbuiltin -mt -compat=5 -library=stlport4 -library=Crun -template=no%extdef ${CXXFLAGS}"
+    CXXFLAGS="-g0 -xO3 -xlibmil -xdepend -xbuiltin -mt -template=no%extdef ${CXXFLAGS}"
   ])
 
   case $host_os in
@@ -67,4 +67,7 @@ AC_DEFUN([ACX_CHECK_SUNCC],[
     ;;
   esac
 
+  AS_IF([test "$target_cpu" = "sparc" -a "x$SUNCC" = "xyes" ],[
+    CXXFLAGS="-xregs=no%appl ${CXXFLAGS}"
+  ])
 ])