Rename devel/oniguruma6 to devel/oniguruma

Details:
- Previous, unmaintained versions of devel/oniguruma have been
  cleared from the ports tree.
- No ports depend on outdated versions of devel/oniguruma.
- Only one version is supported upstream.

PR:		222869
Reported by:	m.bueker@berlin.de
Approved by:	maintainer timeout

MOVED

@@ -9623,3 +9623,4 @@ databases/glom||2017-11-11|Has expired: Broken for more than 6 months
 math/bargraph||2017-11-11|Has expired: Unfetchable for more than six months (google code has gone away)
 devel/oniguruma4|devel/oniguruma6|2017-11-12|Upstream no longer maintained, superseded by devel/oniguruma6
 devel/oniguruma5|devel/oniguruma6|2017-11-12|Upstream no longer maintained, superseded by devel/oniguruma6
+devel/oniguruma6|devel/oniguruma|2017-11-12|Rename devel/oniguruma6 to oniguruma (no other versions in ports tree)

devel/Makefile

@@ -1819,7 +1819,7 @@
     SUBDIR += omniNotify
     SUBDIR += omniORB
     SUBDIR += omniORB-4.1
-    SUBDIR += oniguruma6
+    SUBDIR += oniguruma
     SUBDIR += onscripter
     SUBDIR += onscripter-1byte
     SUBDIR += oozie

devel/oniguruma/Makefile

@@ -19,8 +19,6 @@ GH_ACCOUNT=	kkos
 
 OPTIONS_DEFINE=	DOCS EXAMPLES
 
-CONFLICTS_INSTALL=	oniguruma[45]
-
 PATHFIX_MAKEFILEIN=	Makefile.am
 GNU_CONFIGURE=	yes
 INSTALL_TARGET=	install-strip