gnuplot: Update from 5.0.6 to 5.2.0

packages/gnuplot/src-command.c.patch

@@ -0,0 +1,13 @@
+For WEXITSTATUS macro.
+
+diff -u -r ../gnuplot-5.2.0/src/command.c ./src/command.c
+--- ../gnuplot-5.2.0/src/command.c	2017-08-30 18:48:26.000000000 +0000
++++ ./src/command.c	2017-10-14 20:56:13.905856980 +0000
+@@ -138,6 +138,7 @@
+ int vms_ktid;			/* key table id, for translating keystrokes */
+ #endif /* VMS */
+ 
++#include <sys/wait.h>
+ 
+ /* static prototypes */
+ static void command __PROTO((void));