build: add gzip to prereq-build.mk

gzip has never been checked for, a system without it would be rare, fix
it anyway

Signed-off-by: Tony Butler <[email protected]>

include/prereq-build.mk

@@ -149,6 +149,9 @@ $(eval $(call SetupHostCommand,stat,Cannot find a file stat utility, \
 	gstat -c%s $(TOPDIR)/Makefile, \
 	stat -c%s $(TOPDIR)/Makefile))
 
+$(eval $(call SetupHostCommand,gzip,Please install 'gzip', \
+	gzip --version </dev/null))
+
 $(eval $(call SetupHostCommand,unzip,Please install 'unzip', \
 	unzip 2>&1 | grep zipfile, \
 	unzip))