tools: libelf: install pkg-config file

Install the pkg-config definition for libelf in order to allow the
kernel build process discover it later on.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
(cherry picked from commit d3f86c9cc3e465fbca51aaadbb274856831ba56c)

tools/libelf/Makefile

@@ -37,15 +37,17 @@ define Host/Compile
 endef
 
 define Host/Install
-	$(INSTALL_DIR) $(STAGING_DIR_HOST)/{lib,include/libelf}
+	$(INSTALL_DIR) $(STAGING_DIR_HOST)/{lib/pkgconfig,include/libelf}
 	$(CP) $(HOST_BUILD_DIR)/lib/{elf_repl.h,gelf.h,libelf.h,nlist.h,sys_elf.h} \
 						$(STAGING_DIR_HOST)/include/libelf/
 	$(CP) $(HOST_BUILD_DIR)/lib/libelf.a $(STAGING_DIR_HOST)/lib/
+	$(CP) $(HOST_BUILD_DIR)/libelf.pc $(STAGING_DIR_HOST)/lib/pkgconfig/
 endef
 
 define Host/Clean
 	rm -rf $(STAGING_DIR_HOST)/include/libelf
 	rm -f $(STAGING_DIR_HOST)/lib/libelf.a
+	rm -f $(STAGING_DIR_HOST)/lib/pkgconfig/libelf.pc
 	$(call Host/Clean/Default)
 endef