botan: fix cxx-abi-flags (exported in botan-2.pc)

Signed-off-by: Jürgen Buchmüller <pullmoll@t-online.de>

srcpkgs/botan/template

@@ -1,7 +1,7 @@
 # Template file for 'botan'
 pkgname=botan
 version=2.6.0
-revision=3
+revision=4
 wrksrc="${pkgname^}-${version}"
 build_style=gnu-makefile
 hostmakedepends="doxygen epstopdf python"
@@ -64,7 +64,7 @@ do_configure() {
 
 	python2 configure.py \
 		--distribution-info="Void Linux botan-${version}_${revision}" \
-		--cc-abi-flags="-arch ${_arch} -stdlib=libc++" \
+		--cc-abi-flags="-std=c++14" \
 		--cpu=${_cpu} \
 		${_args}
 }