mk*.sh: use UTC date

mkimage.sh.in

@@ -151,7 +151,7 @@ fi
 # will include the platform the image is being built for and the date
 # on which it was built.
 if [ -z "$FILENAME" ]; then
-    FILENAME="void-${PLATFORM}-$(date +%Y%m%d).img"
+    FILENAME="void-${PLATFORM}-$(date -u +%Y%m%d).img"
 fi
 
 # Create the base image.  This was previously accomplished with dd,

mklive.sh.in

@@ -401,7 +401,7 @@ if [ "$?" -ne "0" ]; then
     die "Failed to find kernel package version"
 fi
 
-: ${OUTPUT_FILE="void-live-${BASE_ARCH}-${KERNELVERSION}-$(date +%Y%m%d).iso"}
+: ${OUTPUT_FILE="void-live-${BASE_ARCH}-${KERNELVERSION}-$(date -u +%Y%m%d).iso"}
 
 print_step "Installing software to generate the image: ${REQUIRED_PKGS} ..."
 install_prereqs

mknet.sh.in

@@ -261,7 +261,7 @@ else
 fi
 
 # Compress the artifacts for distribution
-OUTPUT_FILE="void-${XBPS_TARGET_ARCH}-NETBOOT-$(date +%Y%m%d).tar.gz"
+OUTPUT_FILE="void-${XBPS_TARGET_ARCH}-NETBOOT-$(date -u +%Y%m%d).tar.gz"
 info_msg "Compressing results to $OUTPUT_FILE"
 cd "$BOOT_DIR" || die "Could not enter image dir"
 tar -zcvf "$CURDIR/$OUTPUT_FILE" .

mkplatformfs.sh.in

@@ -222,7 +222,7 @@ fi
 if [ "$COMPRESSION" = "y" ]; then
     # Finally we can compress the tarball, the name will include the
     # platform and the date on which the tarball was built.
-    tarball=${FILENAME:-void-${PLATFORM}-PLATFORMFS-$(date '+%Y%m%d').tar.xz}
+    tarball=${FILENAME:-void-${PLATFORM}-PLATFORMFS-$(date -u '+%Y%m%d').tar.xz}
     run_cmd "tar -cp --posix --xattrs -C $ROOTFS . | xz -T${COMPRESSOR_THREADS:-0} -9 > $tarball "
     [ $? -ne 0 ] && die "Failed to compress tarball"
 

mkrootfs.sh.in

@@ -210,7 +210,7 @@ rm -rf "$ROOTFS/var/cache/*" 2>/dev/null
 
 # Finally we can compress the tarball, the name will include the
 # architecture and the date on which the tarball was built.
-: "${FILENAME:=void-${XBPS_TARGET_ARCH}-ROOTFS-$(date '+%Y%m%d').tar.xz}"
+: "${FILENAME:=void-${XBPS_TARGET_ARCH}-ROOTFS-$(date -u '+%Y%m%d').tar.xz}"
 run_cmd "tar -cp --posix --xattrs -C $ROOTFS . | xz -T${COMPRESSOR_THREADS:-0} -9 > $FILENAME "
 
 # Now that we have the tarball we don't need the rootfs anymore, so we