lpc21isp: fix compilation with glibc

Because -static is being passed, extra linker flags are needed.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

devel/lpc21isp/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=lpc21isp
 PKG_VERSION:=197
-PKG_RELEASE:=4
+PKG_RELEASE:=5
 PKG_LICENSE:=LGPL-3.0-or-later
 PKG_LICENSE_FILES:=README gpl.txt lgpl-3.0.txt
 
@@ -34,6 +34,8 @@ define Package/lpc21isp/description
  and Analog Devices ADUC70xx.
 endef
 
+TARGET_CFLAGS += $(if $(CONFIG_USE_GLIBC),-lc -lgcc_eh)
+
 define Package/lpc21isp/install
 		$(INSTALL_DIR) $(1)/usr/sbin
 		$(INSTALL_BIN) $(PKG_BUILD_DIR)/lpc21isp $(1)/usr/sbin/