[tinderbox] tweak mail subject to avoid gmail confusion

tinderbox/antimatter-scheduler

@@ -19,5 +19,5 @@ CHROOT_PREFIX="${3}"
         /sabayon/bin/antimatter-digest
 ) | mail -a "MIME-Version: 1.0" \
     -a "Content-Type: text/html" \
-    -s "[${ARCH_NAME}] AntiMatter tracker of $(date +%Y-%m-%d)" \
+    -s "AntiMatter tracker of $(date +%Y-%m-%d) for ${ARCH_NAME}" \
     entropy-team@lists.sabayon.org

tinderbox/glsa-scheduler

@@ -17,5 +17,5 @@ CHROOT_PREFIX="${3}"
 (
     ${CHROOT_PREFIX} chroot "${CHROOT_PATH}" \
 	/sabayon/bin/glsa-digest 2>&1
-) | mail -s "[${ARCH_NAME}] GLSA tracker of $(date +%Y-%m-%d)" \
+) | mail -s "GLSA tracker of $(date +%Y-%m-%d) for ${ARCH_NAME}" \
     entropy-team@lists.sabayon.org