bpf-headers: unset PKG_CONFIG_PATH

This fixes an issue where the kernel would pick up an incompatible target
libyaml for building host tools

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/kernel/bpf-headers/Makefile

@@ -41,6 +41,8 @@ define Package/bpf-headers
   HIDDEN:=1
 endef
 
+PKG_CONFIG_PATH:=
+
 export HOST_EXTRACFLAGS=-I$(STAGING_DIR_HOST)/include
 
 KERNEL_MAKE := \