configs/olimex_stmp157: switch to Bootlin glibc stable toolchain

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/olimex_stmp157_olinuxino_lime_defconfig

@@ -1,6 +1,8 @@
 BR2_arm=y
 BR2_cortex_a7=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_10=y
+BR2_TOOLCHAIN_EXTERNAL=y
+BR2_TOOLCHAIN_EXTERNAL_BOOTLIN=y
+BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_ARMV7_EABIHF_GLIBC_STABLE=y
 BR2_GLOBAL_PATCH_DIR="board/olimex/stmp1_olinuxino/patches"
 BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
 BR2_TARGET_GENERIC_HOSTNAME="stmp1-olinuxino"