libv4l: fix glibc compilation

There was a typo in the linker flags.

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

libs/libv4l/Makefile

@@ -7,7 +7,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=v4l-utils
 PKG_VERSION:=1.20.0
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
 PKG_SOURCE_URL:=https://www.linuxtv.org/downloads/v4l-utils
@@ -78,7 +78,7 @@ endef
 TARGET_CFLAGS += -flto
 TARGET_CXXFLAGS += -std=c++11
 TARGET_LDFLAGS += \
-	$(if $(CONFIG_LIBC_USE_GLIBC),,-largp) \
+	$(if $(CONFIG_USE_GLIBC),,-largp) \
 	-Wl,--gc-sections,--as-needed
 
 CONFIGURE_ARGS+= \