[openwrt/openwrt] toolchain: gdb: set -std=gnu17

[LEDE Commits]

robimarko pushed a commit to openwrt/openwrt.git, branch openwrt-24.10:
https://git.openwrt.org/78d517a18cf32402eac016d92d7bb8cc8b586119

commit 78d517a18cf32402eac016d92d7bb8cc8b586119
Author: Robert Marko <robimarko at gmail.com>
AuthorDate: Thu Apr 24 12:31:30 2025 +0200

    toolchain: gdb: set -std=gnu17
    
    Fedora 42 updated to GCC15 which now defaults to GNU23 as the default
    instead of GNU17[1], and this breaks gdb compilation.
    
    This looks like a readline issue, that was fixed in GDB 16.2 but to
    not update toolchain components we can simply set the C standard back
    to GNU17.
    
    [1] https://gcc.gnu.org/gcc-15/porting_to.html#c23
    
    Link: https://github.com/openwrt/openwrt/pull/18581
    Signed-off-by: Robert Marko <robimarko at gmail.com>
---
 toolchain/gdb/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/toolchain/gdb/Makefile b/toolchain/gdb/Makefile
index 9b9ee5a9d8..ad0c843f75 100644
--- a/toolchain/gdb/Makefile
+++ b/toolchain/gdb/Makefile
@@ -56,6 +56,8 @@ else
   HOST_CONFIGURE_ARGS+= --without-python
 endif
 
+HOST_CFLAGS += -std=gnu17
+
 define Host/Install
 	mkdir -p $(TOOLCHAIN_DIR)/bin
 	$(INSTALL_BIN) $(HOST_BUILD_DIR)/gdb/gdb $(TOOLCHAIN_DIR)/bin/$(TARGET_CROSS)gdb