bit fields treating negative values should be declared as signed int

* internal.h (struct vm_ifunc_argc): Bit fields are unsigned by default.
  For storing nagative values to bit fields, they must be declated as
  signed int. Fix multiple test failure observed by 32-bit binaries
  compiled with Oracle Developer Studio (Solaris Studio) 12.x on
  Solaris 10 on sparc architecture. [Bug #14260]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61518 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

internal.h

@@ -914,8 +914,8 @@ struct vm_throw_data {
 
 struct vm_ifunc_argc {
 #if SIZEOF_INT * 2 > SIZEOF_VALUE
-    int min: (SIZEOF_VALUE * CHAR_BIT) / 2;
-    int max: (SIZEOF_VALUE * CHAR_BIT) / 2;
+    signed int min: (SIZEOF_VALUE * CHAR_BIT) / 2;
+    signed int max: (SIZEOF_VALUE * CHAR_BIT) / 2;
 #else
     int min, max;
 #endif