patch that caused regression PR c++/7916

[Janis Johnson]

The regression reported in PR c++/7916 showed up starting with this
patch:

Wed Mar 14 22:26:10 CET 2001  Jan Hubicka  <jh@suse.cz>

	* i386.c (ix86_cmodel_string, ix86_cmodel): Define.
	(override_options): Parse cmodel string.
	(x86_64_sign_extended_value, x86_64_zero_extended_value): New.
	* i386.h (TARGET_OPTIONS): Add "cmodel".
	(EXTRA_CONSTRAINT): Recognize 'e' and 'Z'.
	(enum cmodel): New.
	(ix86_cmodel_string, ix86_cmodel): Declare.

	Spot by Matt Kraai:
	* i386.h (GENERAL_REG_P): Add missing REG_P.

Here's a small test case that causes the compiler to ICE when compiled
on i686-linux.  The PR is against C++, but my testing used cc1 rather
than cc1plus.

-------------------
void foo(char *dst, char xchg, char cmp)
{
  __asm__("lock" "\tcmpxchgb %1, (%2)\t\n"
          :"=al"(cmp)
          :"dl"(xchg), "r"(dst), "al"(cmp));
}
-------------------

Output from the mainline compiler:

7916.c: In function `foo':
7916.c:6: internal compiler error: in instantiate_virtual_regs_1,
          at function.c:3898
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.

I've added this information to the PR.

Jan, if the testcase itself isn't valid then please add that
information to the PR.

Janis