Mk/bsd.port.mk: Sunset MANPREFIX

For historical reasons FreeBSD had been using PREFIX/man to install man
pages and a variable MANPREFIX was utilized to do this. While the rest
of the UNIX/Linux world had been mostly using PREFIX/share. As the
first step of moving to PREFIX/share/man this commit removes all the
references to the MANPREFIX variable. Apart from MAKE_ARGS this
variable no longer exists and should not be used to refer to PREFIX
anymore in the future.

The entire shift to PREFIX/share/man will take some more times as there
are around 4000 ports which installs man page to PREFIX/man.

PR:		276551
Approved by:	portmgr (exp-run)

Mk/bsd.port.mk

@@ -501,9 +501,6 @@ FreeBSD_MAINTAINER=	portmgr@FreeBSD.org
 #				  Installs all directories and files from ${WRKSRC}/doc
 #				  to ${DOCSDIR} except sed(1) backup files.
 #
-# MANPREFIX		- The directory prefix for manual pages.
-#				  Default: ${PREFIX}
-#
 # Set the following to specify all .info files your port installs.
 #
 # INFO			- A list of .info files (omitting the trailing ".info");
@@ -752,7 +749,7 @@ FreeBSD_MAINTAINER=	portmgr@FreeBSD.org
 #				- Pass these args to configure if ${HAS_CONFIGURE} is set.
 #				  Default: "--prefix=${GNU_CONFIGURE_PREFIX}
 #				  --infodir=${PREFIX}/${INFO_PATH} --localstatedir=/var
-#				  --mandir=${MANPREFIX}/man --build=${CONFIGURE_TARGET}" if
+#				  --mandir=${PREFIX}/man --build=${CONFIGURE_TARGET}" if
 #				  GNU_CONFIGURE is set, "CC=${CC} CFLAGS=${CFLAGS}
 #				  PREFIX=${PREFIX} INSTALLPRIVLIB=${PREFIX}/lib
 #				  INSTALLARCHLIB=${PREFIX}/lib" if USES=perl5 and
@@ -2028,8 +2025,7 @@ MAKE_ENV+=		PREFIX=${PREFIX} \
 			CC="${CC}" CFLAGS="${CFLAGS}" \
 			CPP="${CPP}" CPPFLAGS="${CPPFLAGS}" \
 			LDFLAGS="${LDFLAGS}" LIBS="${LIBS}" \
-			CXX="${CXX}" CXXFLAGS="${CXXFLAGS}" \
-			MANPREFIX="${MANPREFIX}"
+			CXX="${CXX}" CXXFLAGS="${CXXFLAGS}"
 
 # Add -fno-strict-aliasing to CFLAGS with optimization level -O2 or higher.
 # gcc 4.x enable strict aliasing optimization with -O2 which is known to break
@@ -2701,7 +2697,7 @@ CONFIGURE_MAX_CMD_LEN!=	${SYSCTL} -n kern.argmax
 .      endif
 _EXPORTED_VARS+=	CONFIGURE_MAX_CMD_LEN
 GNU_CONFIGURE_PREFIX?=	${PREFIX}
-GNU_CONFIGURE_MANPREFIX?=	${MANPREFIX}
+GNU_CONFIGURE_MANPREFIX?=	${PREFIX}
 CONFIGURE_ARGS+=	--prefix=${GNU_CONFIGURE_PREFIX} $${_LATE_CONFIGURE_ARGS}
 .      if defined(CROSS_TOOLCHAIN)
 CROSS_HOST=		${ARCH:S/amd64/x86_64/}-unknown-${OPSYS:tl}${OSREL}
@@ -2745,14 +2741,9 @@ SCRIPTS_ENV+=	CURDIR=${MASTERDIR} DISTDIR=${DISTDIR} \
 SCRIPTS_ENV+=	BATCH=yes
 .    endif
 
-.    if ${PREFIX} == /usr
-MANPREFIX?=	/usr/share
-.    else
-MANPREFIX?=	${PREFIX}
 MANDIRS+=	${PREFIX}/share/man
-.    endif
 
-MANDIRS+=	${MANPREFIX}/man
+MANDIRS+=	${PREFIX}/man
 INFO_PATH?=	share/info
 
 .    if defined(INFO)