portmap: improve installation of binaries

This commit explicits the permissions with which executables are
installed, and also makes sure that the build is aborted if one of the
binaries cannot be installed, instead of silently ignoring the error.

[Peter: fixop typos in commit message as noted by Yann]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/portmap/portmap.mk

@@ -22,7 +22,7 @@ endef
 
 define PORTMAP_INSTALL_TARGET_CMDS
 	for sbin in $(PORTMAP_SBINS); do \
-		$(INSTALL) -D $(@D)/$$sbin $(TARGET_DIR)/sbin/$$sbin; \
+		$(INSTALL) -D -m 0755 $(@D)/$$sbin $(TARGET_DIR)/sbin/$$sbin || exit 1; \
 	done
 endef