krb5: install gssapi_krb5/gssapi/gssapi.h once

Somewhat arbitrarily chose krb5/lib/gssapi/Makefile to install it.

PR:		288594
Pull Request:	https://github.com/freebsd/freebsd-src/pull/1801

krb5/include/Makefile

@@ -17,7 +17,7 @@ SUBDIR=	krb5_private krb5 gssrpc gssapi
 
 SUBDIR_PARALLEL=
 
-INCSGROUPS=	INCS GSSAPI_KRB5
+INCSGROUPS=	INCS
 
 INCSDIR=	${INCLUDEDIR}
 
@@ -27,9 +27,6 @@ INCS=	kdb.h \
 	krad.h \
 	krb5.h
 
-GSSAPI_KRB5DIR=	${INCLUDEDIR}/gssapi_krb5/gssapi
-GSSAPI_KRB5=	gssapi.h
-
 CLEANFILES=	osconf.new
 
 # XXX The output of this needs to be verified against the osconf.h I created