include: relax umask check

For now we only want to ensure that the group permission mask is permissive
enough to not clobber required permissions on the rootfs, so allow less
strict masks as well.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

include/prereq-build.mk

@@ -26,7 +26,7 @@ $(eval $(call TestHostCommand,case-sensitive-fs, \
 
 $(eval $(call TestHostCommand,proper-umask, \
 	Please build with umask 022 - other values produce broken packages, \
-	umask | grep -xF 0022))
+	umask | grep -xE 00[012][012]))
 
 $(eval $(call SetupHostCommand,gcc, \
 	Please install the GNU C Compiler (gcc), \