treewide: add support for "gc-sections" in PKG_BUILD_FLAGS

This reduces open coding and allows to easily add a knob to
enable it treewide, where chosen packages can still opt-out via
"no-gc-sections".

Note: libnl, mbedtls and opkg only used the CFLAGS part without the
LDFLAGS counterpart. That doesn't help at all if the goal is to produce
smaller binaries. I consider that an accident, and this fixes it.

Note: there are also packages using only the LDFLAGS part. I didn't
touch those, as gc might have been disabled via CFLAGS intentionally.

Signed-off-by: Andre Heider <a.heider@gmail.com>

4 files changed, 10 insertions, 8 deletions

diff --git a/package/libs/libevent2/Makefile b/package/libs/libevent2/Makefile
index 85c159c2a6..50dd19bf00 100644
--- a/package/libs/libevent2/Makefile
+++ b/package/libs/libevent2/Makefile
@@ -26,6 +26,8 @@ PKG_CONFIG_DEPENDS:= \
 	CONFIG_PACKAGE_libevent2-pthreads \
 	CONFIG_PACKAGE_libevent2-mbedtls
 
+PKG_BUILD_FLAGS:=gc-sections
+
 include $(INCLUDE_DIR)/package.mk
 include $(INCLUDE_DIR)/cmake.mk
 
@@ -112,8 +114,8 @@ define Package/libevent2-pthreads/description
 	threading & locking.
 endef
 
-TARGET_CFLAGS += $(FPIC) -ffunction-sections -fdata-sections -flto
-TARGET_LDFLAGS += -Wl,--gc-sections,--as-needed -flto
+TARGET_CFLAGS += $(FPIC) -flto
+TARGET_LDFLAGS += -Wl,--as-needed -flto
 
 CMAKE_OPTIONS += \
 	-DEVENT__DISABLE_BENCHMARK:BOOL=ON \
diff --git a/package/libs/libnl/Makefile b/package/libs/libnl/Makefile
index 71b043a9e5..56549dcc0a 100644
--- a/package/libs/libnl/Makefile
+++ b/package/libs/libnl/Makefile
@@ -20,6 +20,8 @@ PKG_CPE_ID:=cpe:/a:libnl_project:libnl
 PKG_INSTALL:=1
 PKG_FIXUP:=autoreconf
 
+PKG_BUILD_FLAGS:=gc-sections
+
 include $(INCLUDE_DIR)/package.mk
 
 define Package/libnl/default
@@ -80,7 +82,7 @@ define Package/libnl/description
  message construction and parsing, object caching system, etc.
 endef
 
-TARGET_CFLAGS += -ffunction-sections -fdata-sections $(FPIC)
+TARGET_CFLAGS += $(FPIC)
 
 CONFIGURE_ARGS += \
 	--disable-debug
diff --git a/package/libs/mbedtls/Makefile b/package/libs/mbedtls/Makefile
index 7c167e2296..f49bb24de6 100644
--- a/package/libs/mbedtls/Makefile
+++ b/package/libs/mbedtls/Makefile
@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=mbedtls
 PKG_VERSION:=2.28.2
 PKG_RELEASE:=2
-PKG_BUILD_FLAGS:=no-mips16
+PKG_BUILD_FLAGS:=no-mips16 gc-sections
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://codeload.github.com/ARMmbed/mbedtls/tar.gz/v$(PKG_VERSION)?
@@ -121,7 +121,6 @@ This package contains mbedtls helper programs for private key and
 CSR generation (gen_key, cert_req)
 endef
 
-TARGET_CFLAGS += -ffunction-sections -fdata-sections
 TARGET_CFLAGS := $(filter-out -O%,$(TARGET_CFLAGS))
 
 CMAKE_OPTIONS += \
diff --git a/package/libs/openssl/Makefile b/package/libs/openssl/Makefile
index 7918d40347..9fe5da9dd3 100644
--- a/package/libs/openssl/Makefile
+++ b/package/libs/openssl/Makefile
@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=openssl
 PKG_VERSION:=3.0.8
 PKG_RELEASE:=4
-PKG_BUILD_FLAGS:=no-mips16
+PKG_BUILD_FLAGS:=no-mips16 gc-sections
 
 PKG_BUILD_PARALLEL:=1
 
@@ -339,8 +339,7 @@ define Build/Configure
 	)
 endef
 
-TARGET_CFLAGS += $(FPIC) -ffunction-sections -fdata-sections
-TARGET_LDFLAGS += -Wl,--gc-sections
+TARGET_CFLAGS += $(FPIC)
 
 define Build/Compile
 	+$(MAKE) $(PKG_JOBS) -C $(PKG_BUILD_DIR) \