CLEANUP: cfgparse: replace "realloc" with "my_realloc2" to fix to memory leak on error

my_realloc2 frees variable in case of allocation failure.

fixes #1030

realloc was introduced in 9e1758efbd

this might be backported to 2.2, 2.3

src/cfgparse.c

@@ -1983,7 +1983,7 @@ int readcfgfile(const char *file)
 
 			if (err & (PARSE_ERR_TOOLARGE|PARSE_ERR_OVERLAP)) {
 				outlinesize = (outlen + 1023) & -1024;
-				outline = realloc(outline, outlinesize);
+				outline = my_realloc2(outline, outlinesize);
 				if (outline == NULL) {
 					ha_alert("parsing [%s:%d]: line too long, cannot allocate memory.\n",
 						 file, linenum);