package/gnuplot: add patch to fix 'undefined reference to gp_read_history'

Fixes:
 - http://autobuild.buildroot.net/results/e09087f0afd323a220889e2c7827fd73c9025673

Signed-off-by: Michael Fischer <mf@go-sys.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/gnuplot/0002-without-history.patch

@@ -0,0 +1,17 @@
+history.c: Patch to solve the 'undefined reference to gp_read_history'
+
+Signed-off-by: Michael Fischer <mf@go-sys.de>
+
+diff -purN gnuplot-5.4.0.org/src/history.c gnuplot-5.4.0/src/history.c
+--- gnuplot-5.4.0.org/src/history.c	2019-12-10 07:22:32.000000000 +0100
++++ gnuplot-5.4.0/src/history.c	2020-09-14 10:07:36.525441702 +0200
+@@ -91,7 +91,9 @@ write_history(char *filename)
+ void
+ read_history(char *filename)
+ {
+-    gp_read_history(filename);
++#ifdef GNUPLOT_HISTORY
++    	gp_read_history(filename);
++#endif	
+ }
+