patch 9.0.0378: compiler warning for uninitialized variable

Problem:    Compiler warning for uninitialized variable. (Tony Mechelynck)
Solution:   Initialize it.
diff --git a/src/spellfile.c b/src/spellfile.c
index 69b27ae..d650f87 100644
--- a/src/spellfile.c
+++ b/src/spellfile.c
@@ -841,7 +841,7 @@
 read_region_section(FILE *fd, slang_T *lp, int len)
 {
     int		i;
-    int		c;
+    int		c = 0;
 
     if (len > MAXREGIONS * 2)
 	return SP_FORMERROR;