Resurrect `math/grpn' removed in r487992 because it used obsolete GTK+

stack.  This version is a picked up fork on GitHub which now supports
GTK+ 2.0 and include a number of bugfixes, so welcome back!

Requested by:	someone on #bsdports

math/Makefile

@@ -265,6 +265,7 @@
     SUBDIR += gretl
     SUBDIR += gri
     SUBDIR += gringo
+    SUBDIR += grpn
     SUBDIR += gsl
     SUBDIR += hexcalc
     SUBDIR += hipmcl

math/grpn/Makefile

@@ -0,0 +1,34 @@
+# Created by: Chris D. Faulhaber <jedgar@fxp.org>
+# $FreeBSD$
+
+PORTNAME=	grpn
+PORTVERSION=	1.5.2
+DISTVERSIONPREFIX=	v
+CATEGORIES=	math
+
+MAINTAINER=	ports@FreeBSD.org
+COMMENT=	GTK+-based reverse polish notation (RPN) calculator
+
+LICENSE=	GPLv2
+
+USES=		gnome pkgconfig
+USE_GNOME=	gtk20
+USE_GITHUB=	yes
+GH_ACCOUNT=	utopiabound
+
+WRKSRC_SUBDIR=	src
+
+PLIST_FILES=	bin/grpn man/man1/grpn.1.gz
+PORTDOCS=	CHANGES
+
+OPTIONS_DEFINE=	DOCS
+
+post-patch:
+	@${REINPLACE_CMD} -e 's,ulong,unsigned long,g' \
+		${WRKSRC}/real.c
+
+post-install-DOCS-on:
+	@${MKDIR} ${STAGEDIR}${DOCSDIR}
+	${INSTALL_DATA} ${PORTDOCS:S|^|${WRKSRC}/|} ${STAGEDIR}${DOCSDIR}
+
+.include <bsd.port.mk>

math/grpn/distinfo

@@ -0,0 +1,3 @@
+TIMESTAMP = 1543025897
+SHA256 (utopiabound-grpn-v1.5.2_GH0.tar.gz) = 36a306ee7ac840c2f114877b07ee70688d53dd3111773938ae816c8b90d3e99d
+SIZE (utopiabound-grpn-v1.5.2_GH0.tar.gz) = 61799

math/grpn/files/patch-Makefile

@@ -0,0 +1,38 @@
+--- Makefile.orig	2018-11-24 02:18:17 UTC
++++ Makefile
+@@ -3,11 +3,11 @@
+ # Please read the next few lines and enter the correct values.
+ 
+ # where to install GRPN
+-PREFIX = /usr/local
+-MANDIR = ${PREFIX}/man
++PREFIX ?= /usr/local
++MANDIR ?= ${MANPREFIX}/man
+ 
+ # What compiler should be used
+-CC = gcc 
++CC ?= gcc
+ 
+ # NOTE:
+ #
+@@ -16,10 +16,8 @@ CC = gcc 
+ # add -DUSE_GNOME if you want to make grpn GNOME compliant.
+ 
+ 
+-CFLAGS = -Wall -g -O2 -I/usr/X11/include -DUSE_PANGO `pkg-config --cflags gtk+-2.0` -DGTK_VER_1_1
++CFLAGS += -Wall -DUSE_PANGO `pkg-config --cflags gtk+-2.0` -DGTK_VER_1_1
+ 
+-DFLAGS =  -L/usr/X11/lib 
+-
+ # end of user configurable section
+ 
+ 
+@@ -32,6 +30,8 @@ OBJS = test_gtk_ver.o real.o complex.o matrix.o number
+ 	error.o help.o mode.o undo.o
+ 
+ LIBS   = `pkg-config --libs gtk+-2.0` -lX11 -lm
++
++all: grpn
+ 
+ grpn:	$(OBJS)
+ 	$(CC) $(DFLAGS) -o $@ $(OBJS) $(LIBS) 

math/grpn/pkg-descr

@@ -0,0 +1,9 @@
+GRPN is a RPN calculator for the X Window system built using
+the GIMP Toolkit (GTK).
+
+GRPN works with real numbers, complex numbers, matrices, and
+complex matrices.  Numbers can be displayed in 4 different
+radix modes, and complex numbers can be displayed in either
+Cartesian or polar form.
+
+WWW: https://github.com/utopiabound/grpn