linux: fix PATH_MAX macro redefined in exec-cmd.c on macOS 15.4

Fix an error while building target/linux on macOS 15.4 host,
due to the PATH_MAX macro being redefined:

mkdir -p /Volumes/test/openwrt/build_dir/target-x86_64_musl/linux-x86_64/linux-6.6.86/tools/objtool && make O=/Volumes/test/openwrt/build_dir/target-x86_64_musl/linux-x86_64/linux-6.6.86 subdir=tools/objtool --no-print-directory -C objtool
exec-cmd.c:15:9: error: 'PATH_MAX' macro redefined [-Werror,-Wmacro-redefined]
   15 | #define PATH_MAX        4096
      |         ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys/syslimits.h:103:9: note: previous definition is here
  103 | #define PATH_MAX                 1024   /* max bytes in pathname */
      |         ^

exec-cmd.c is compiled as part of objtool to run on the host, and
therefore host headers are used, where PATH_MAX is already defined.
Using an old OpenWRT snapshot from 2025-02-16, where linux-6.6.77
used to build correctly, does not help. Reveting from Xcode 16.3 to
16.2 does not help either.

Signed-off-by: Georgi Valkov <[email protected]>

Author: httpstorm

target/linux/x86/patches-6.6/104-exec-cmd.fix-PATH_MAX-redefined-macOS-15.4.patch

@@ -0,0 +1,46 @@
+From 0c1759139188c0873f288758fe57366ed1291c2a Mon Sep 17 00:00:00 2001
+From: Georgi Valkov <[email protected]>
+Date: Fri, 18 Apr 2025 16:08:16 +0300
+Subject: [PATCH] tools/objtool: fix PATH_MAX macro redefined-build OpenWRT on
+ macOS 15.4
+
+Fix an error while building linux as part of OpenWRT on macOS 15.4 host,
+due to the PATH_MAX macro being redefined:
+
+mkdir -p /Volumes/test/openwrt/build_dir/target-x86_64_musl/linux-x86_64/linux-6.6.86/tools/objtool && make O=/Volumes/test/openwrt/build_dir/target-x86_64_musl/linux-x86_64/linux-6.6.86 subdir=tools/objtool --no-print-directory -C objtool
+exec-cmd.c:15:9: error: 'PATH_MAX' macro redefined [-Werror,-Wmacro-redefined]
+   15 | #define PATH_MAX        4096
+      |         ^
+/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys/syslimits.h:103:9: note: previous definition is here
+  103 | #define PATH_MAX                 1024   /* max bytes in pathname */
+      |         ^
+
+exec-cmd.c is compiled as part of objtool to run on the host, and
+therefore host headers are used, where PATH_MAX is already defined.
+Using an old OpenWRT snapshot from 2025-02-16, where linux-6.6.77
+used to build correctly, does not help. Reveting from Xcode 16.3 to
+16.2 does not help either.
+
+Signed-off-by: Georgi Valkov <[email protected]>
+---
+ tools/lib/subcmd/exec-cmd.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/tools/lib/subcmd/exec-cmd.c b/tools/lib/subcmd/exec-cmd.c
+index 7739b5217cf6..dc82cacd82cb 100644
+--- a/tools/lib/subcmd/exec-cmd.c
++++ b/tools/lib/subcmd/exec-cmd.c
+@@ -12,7 +12,10 @@
+ #include "subcmd-config.h"
+ 
+ #define MAX_ARGS	32
++
++#ifndef PATH_MAX
+ #define PATH_MAX	4096
++#endif
+ 
+ static const char *argv_exec_path;
+ static const char *argv0_path;
+-- 
+2.49.0
+