[gcc r12-5592] libgcc: vxcrtstuff.c: add a few undefs

[Rasmus Villemoes <villemoes@gcc.gnu.org>]

https://gcc.gnu.org/g:930e7637828b6c6da7ff33ff3bd20c5c4c9164e7

commit r12-5592-g930e7637828b6c6da7ff33ff3bd20c5c4c9164e7
Author: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Date:   Fri Oct 29 10:10:12 2021 +0200

    libgcc: vxcrtstuff.c: add a few undefs
    
    When vxcrtstuff.c was created, the set of #includes was copied from
    crtstuff.c. But crtstuff.c also has a bunch of #undefs after the first
    #include, because, as the comment says, including auto-host.h when
    building objects that are meant for target is technically not
    correct.
    
    This manifests when I try do do a canadian cross, with build=linux,
    host=windows and target=vxworks, in that we pick up a
    
      #define caddr_t char *
    
    from auto-host.h, which then of course creates a problem when we later
    include a target header that has
    
      typedef char * caddr_t;
    
    I assume that the #undefs in crtstuff.c have been added for similar
    reasons.
    
    These potentially problematic #defines all seem to be guarded by
    #ifndef USED_FOR_TARGET, which tconfig.h defines before including
    auto-host.h. So at first, it seems that one could avoid the problem
    by simply removing the initial include of auto-host.h. Unfortunately,
    we do need some of the things defined in auto-host.h within such an
    ifndef USED_FOR_TARGET, namely the define of
    HAVE_INITFINI_ARRAY_SUPPORT, which is what later causes
    initfini-array.h to define USE_INITFINI_ARRAY. So as the next best
    fix, just copy the #undefs from crtstuff.c.
    
    libgcc/
            * config/vxcrtstuff.c: Undefine caddr_t, pid_t, rlim_t,
            ssize_t and vfork after including auto-host.h.

Diff:
---
 libgcc/config/vxcrtstuff.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libgcc/config/vxcrtstuff.c b/libgcc/config/vxcrtstuff.c
index 87fadda9ac5..767b9de577d 100644
--- a/libgcc/config/vxcrtstuff.c
+++ b/libgcc/config/vxcrtstuff.c
@@ -26,7 +26,15 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 
 #define IN_LIBGCC2
 
+/* FIXME: Including auto-host is incorrect, but until we have
+   identified the set of defines that need to go into auto-target.h,
+   this will have to do.  */
 #include "auto-host.h"
+#undef caddr_t
+#undef pid_t
+#undef rlim_t
+#undef ssize_t
+#undef vfork
 #include "tconfig.h"
 #include "tsystem.h"
 #include "coretypes.h"