[PATCH] [gdb/build] Fix C inclusion of nat/x86-cpuid.h

[Tom de Vries via Gdb-patches <gdb-patches@sourceware.org>]

When running test-case gdb.arch/i386-avx512.exp, I run into:
...
 gdb compile failed, In file included from gdb.arch/i386-avx512.c:20:0:
 src/gdb/nat/x86-cpuid.h: In function 'x86_cpuid_count':
 src/gdb/nat/x86-cpuid.h:63:16: error: \
   'nullptr' undeclared (first use in this function)
    if (__eax == nullptr)
                 ^~~~~~~
 src/gdb/nat/x86-cpuid.h:63:16: note: each \
   undeclared identifier is reported only once for each function it appears in

                  === gdb Summary ===

 # of untested testcases         1
...

This is due to commit e85aad4ae76 ("nat/x86-cpuid.h: Add x86_cpuid_count
wrapper around __get_cpuid_count"), which introduced the nullptr check.

The header file gdb/nat/x86-cpuid.h is a file that is included in the build
and compiled as a C++ file, but also in the testsuite and compiled as a C
file.

Fix this by replacing nullptr with (void *)0.

Tested on x86_64-linux.
---
 gdb/nat/x86-cpuid.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/gdb/nat/x86-cpuid.h b/gdb/nat/x86-cpuid.h
index 517113d45e8..25a08f4e94e 100644
--- a/gdb/nat/x86-cpuid.h
+++ b/gdb/nat/x86-cpuid.h
@@ -60,13 +60,13 @@ x86_cpuid_count (unsigned int __level, unsigned int __sublevel,
 {
   unsigned int __scratch;
 
-  if (__eax == nullptr)
+  if (__eax == (void *)0)
     __eax = &__scratch;
-  if (__ebx == nullptr)
+  if (__ebx == (void *)0)
     __ebx = &__scratch;
-  if (__ecx == nullptr)
+  if (__ecx == (void *)0)
     __ecx = &__scratch;
-  if (__edx == nullptr)
+  if (__edx == (void *)0)
     __edx = &__scratch;
 
   return __get_cpuid_count (__level, __sublevel, __eax, __ebx, __ecx, __edx);

base-commit: 8468e03688622f265529699e2efd355a4c122cc6
-- 
2.35.3