revert change to cairotrm_reset

ChangeLog

@@ -1,3 +1,7 @@
+2017-09-20  Ethan A Merritt  <merritt@u.washington.edu>
+
+	* term/cairo.trm (cairotrm_reset):  Revert change.
+
 2017-09-19  Ethan A Merritt  <merritt@u.washington.edu>
 
 	* term/cairo.trm (cairotrm_init cairotrm_reset):  Valgrind complained
@@ -6,6 +10,8 @@
 	It does make sense to call it if the terminal has been closed and then
 	reopened.  So we fix the ordering of code in cairotrm_init that
 	frees the old plot.cr before reinitializing a new one.
+	REVERT: This change caused some cairo installations to close pdf output
+	file without proper termination of the contents.
 
 	* src/parse.c (parse_array_assignment):  Memory leak.
 

term/cairo.trm

@@ -1,5 +1,5 @@
 /* Hello, Emacs: this is -*-C-*- !
- * $Id: cairo.trm,v 1.80 2017-09-19 20:15:10 sfeam Exp $
+ * $Id: cairo.trm,v 1.81 2017-09-21 18:22:12 sfeam Exp $
  */
 
 /* GNUPLOT - cairo.trm */
@@ -973,13 +973,8 @@ void cairotrm_text()
 /* sent when gnuplot exits and when the terminal or the output change.*/
 void cairotrm_reset()
 {
-	/* Sep 2017
-	 * valgrind complains that this triggers reads of already-freed data.
-	 * It is unclear whether that is a real problem, but it is also unclear
-	 * that anything is gained by explicit cleanup when we are about to exit.
-	 * Let's try skipping it and see if anyone notices.
-	 */
-	/* cairo_destroy(plot.cr); */
+	if (plot.cr)
+		cairo_destroy(plot.cr);
 
 #ifdef PSLATEX_DRIVER
 	/* finish latex output */