List one MIB per line

This is easier to edit.

mibs/Makefile.am

@@ -1,3 +1,16 @@
 mibsdir = $(NETSNMP_MIBPATH)
-mibs_DATA = CLAB-DEF-MIB DOCS-BPI-MIB DOCS-BPI2-MIB DOCS-CABLE-DEVICE-MIB DOCS-CABLE-DEVICE-TRAP-MIB DOCS-IF-EXT-MIB DOCS-IF-MIB DOCS-QOS-MIB DOCS-SUBMGT-MIB IGMP-STD-MIB PKTC-EVENT-MIB PKTC-MTA-MIB PKTC-SIG-MIB
+mibs_DATA = \
+	CLAB-DEF-MIB \
+	DOCS-BPI2-MIB \
+	DOCS-BPI-MIB \
+	DOCS-CABLE-DEVICE-MIB \
+	DOCS-CABLE-DEVICE-TRAP-MIB \
+	DOCS-IF-EXT-MIB \
+	DOCS-IF-MIB \
+	DOCS-QOS-MIB \
+	DOCS-SUBMGT-MIB \
+	IGMP-STD-MIB \
+	PKTC-EVENT-MIB \
+	PKTC-MTA-MIB \
+	PKTC-SIG-MIB
 EXTRA_DIST = $(mibs_DATA)