[openwrt/openwrt] toolchain/gcc: enable zstd support

[LEDE Commits]

ansuel pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/acc8c2d829fb5e0e0b2495d720e058f91ea164b0

commit acc8c2d829fb5e0e0b2495d720e058f91ea164b0
Author: Andre Heider <a.heider at gmail.com>
AuthorDate: Sun Feb 5 23:21:46 2023 +0100

    toolchain/gcc: enable zstd support
    
    LTO object files will now be compressed using zstd.
    
    Compressing debug sections with zstd will have to wait for GCC 13,
    which adds support for -gz=zstd.
    
    NOTE: wiping the ccache is strongly recommended, not doing so might
    yield build error later on:
    "lto1: internal compiler error: original not compressed with zstd"
    
    Signed-off-by: Andre Heider <a.heider at gmail.com>
---
 toolchain/gcc/common.mk | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/toolchain/gcc/common.mk b/toolchain/gcc/common.mk
index e885141538..25f7e1ef70 100644
--- a/toolchain/gcc/common.mk
+++ b/toolchain/gcc/common.mk
@@ -66,6 +66,9 @@ TAR_OPTIONS += \
 	--exclude-from='$(CURDIR)/../exclude-testsuite' --exclude=gcc/ada/*.ad* \
 	--exclude=libjava
 
+# this needs to be without -L/-lzstd flags or other parts fail to build
+# use an absolute path to ensure it really picks up our version
+export ac_cv_search_ZSTD_compress=$(STAGING_DIR_HOST)/lib/libzstd.a -pthread
 export libgcc_cv_fixed_point=no
 ifdef CONFIG_INSTALL_GCCGO
   export libgo_cv_c_split_stack_supported=no
@@ -103,7 +106,7 @@ GCC_CONFIGURE:= \
 		$(if $(CONFIG_arc),--with-cpu=$(CONFIG_CPU_TYPE)) \
 		$(if $(CONFIG_powerpc64), $(if $(CONFIG_USE_MUSL),--with-abi=elfv2)) \
 		--with-system-zlib=$(STAGING_DIR_HOST) \
-		--without-zstd \
+		--with-zstd=$(STAGING_DIR_HOST) \
 		--with-gmp=$(STAGING_DIR_HOST) \
 		--with-mpfr=$(STAGING_DIR_HOST) \
 		--with-mpc=$(STAGING_DIR_HOST) \