wolfssl: Activate link time optimization (LTO)

The ipk sizes for mips_24Kc change like this:
old:
libwolfssl24_4.5.0-stable-1_mips_24kc.ipk	391.545

new:
libwolfssl24_4.5.0-stable-2_mips_24kc.ipk	387.439

Signed-off-by: Hauke Mehrtens <[email protected]>

package/libs/wolfssl/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=wolfssl
 PKG_VERSION:=4.5.0-stable
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://github.com/wolfSSL/wolfssl/archive/v$(PKG_VERSION)
@@ -56,7 +56,8 @@ define Package/libwolfssl/config
 	source "$(SOURCE)/Config.in"
 endef
 
-TARGET_CFLAGS += $(FPIC) -DFP_MAX_BITS=8192 -fomit-frame-pointer
+TARGET_CFLAGS += $(FPIC) -DFP_MAX_BITS=8192 -fomit-frame-pointer -flto
+TARGET_LDFLAGS += -flto
 
 # --enable-stunnel needed for OpenSSL API compatibility bits
 CONFIGURE_ARGS += \