Merge pull request #5781 from kaspar030/add_ltoflags_to_riotbuild.h

make: add LTOFLAGS to CFLAGS used to generate riotbuild.h

dist/tools/genconfigheader/genconfigheader.sh

@@ -42,6 +42,9 @@ set -e
 
 echo "/* DO NOT edit this file, your changes will be overwritten and won't take any effect! */" > "${TMPFILE}"
 echo "/* Generated from CFLAGS: $@ */" >> "${TMPFILE}"
+
+[ -n "${LTOFLAGS}" ] && echo "/* LTOFLAGS=${LTOFLAGS} */" >> "${TMPFILE}"
+
 for arg in "$@"; do
   case ${arg} in
     -D*)