[gcc r10-9499] Darwin: Guard two macros in darwin.h.

[Iain D Sandoe]

https://gcc.gnu.org/g:aa55f33e6cb5cd1ff21f53e2855f52590135f01f

commit r10-9499-gaa55f33e6cb5cd1ff21f53e2855f52590135f01f
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Sun Aug 2 16:44:02 2020 +0100

    Darwin: Guard two macros in darwin.h.
    
    Work on the Arm64 port shows that these two macros can be declared
    ahead of the version in darwin.h which needs to override (for X86
    and PPC this wasn't needed).
    
    gcc/ChangeLog:
    
            * config/darwin.h (ASM_DECLARE_FUNCTION_NAME): UNDEF before
            use.
            (DEF_MIN_OSX_VERSION): Only define if there's no existing
            def.
    
    (cherry picked from commit 105fe3e0b896998b4a1b5a79ad6526959c2e2e7a)

Diff:
---
 gcc/config/darwin.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index f528b1766bf..55a5361cadb 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -652,6 +652,7 @@ extern GTY(()) int darwin_ms_struct;
    that the name *is* defined in this module, so it doesn't need to
    make them indirect.  */
 
+#undef ASM_DECLARE_FUNCTION_NAME
 #define ASM_DECLARE_FUNCTION_NAME(FILE, NAME, DECL)			\
   do {									\
     const char *xname = NAME;						\
@@ -1059,7 +1060,9 @@ extern void darwin_driver_init (unsigned int *,struct cl_decoded_option **);
    providing an osx-version-min of this unless overridden by the User.
    10.5 is the only version that fully supports all our archs so that's the
    fall-back default.  */
+#ifndef DEF_MIN_OSX_VERSION
 #define DEF_MIN_OSX_VERSION "10.5"
+#endif
 
 /* Later versions of ld64 support coalescing weak code/data without requiring
    that they be placed in specially identified sections.  This is the earliest