[openwrt/openwrt] toolchain/libstdcpp: disable dual ABI and default to new

[LEDE Commits]

aparcar pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/01e4274c2117863603363c22f403af159c71cbfd

commit 01e4274c2117863603363c22f403af159c71cbfd
Author: Rosen Penev <rosenp at gmail.com>
AuthorDate: Wed Jan 20 20:51:45 2021 -0800

    toolchain/libstdcpp: disable dual ABI and default to new
    
    GCC 5.1 changed the std::string ABI in order to properly support C++11.
    For compatibility with libraries compiled with the older ABI, that is,
    linking between old-abi.so and new-abi.bin, both ABIs are enabled. In
    terms of OpenWrt, all packages are compiled with the same toolchain,
    which means these issues do not need to be handled.
    
    Most importantly, this results in a significant size reduction of
    libstdpp:
    
    Before:
    
    450794 bytes
    
    After:
    
    327752 bytes
    
    Tested with all OpenWrt packages.
    
    Signed-off-by: Rosen Penev <rosenp at gmail.com>
---
 toolchain/gcc/common.mk | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/toolchain/gcc/common.mk b/toolchain/gcc/common.mk
index aaddb74642..55fad1fcc4 100644
--- a/toolchain/gcc/common.mk
+++ b/toolchain/gcc/common.mk
@@ -117,7 +117,9 @@ GCC_CONFIGURE:= \
 		--with-mpc=$(TOPDIR)/staging_dir/host \
 		--disable-decimal-float \
 		--with-diagnostics-color=auto-if-env \
-		--enable-__cxa_atexit
+		--enable-__cxa_atexit \
+		--disable-libstdcxx-dual-abi \
+		--with-default-libstdcxx-abi=new
 ifneq ($(CONFIG_mips)$(CONFIG_mipsel),)
   GCC_CONFIGURE += --with-mips-plt
 endif