Add spaces around '/*' and '*/'

Like most other Qt coding styles, the necessary spaces should be added
to the sides of '/*' and '*/'
diff --git a/png.c b/png.c
index a4a239a..12f4050 100644
--- a/png.c
+++ b/png.c
@@ -1843,12 +1843,12 @@
 #  ifdef PNG_WARNINGS_SUPPORTED
    else
       {
-         char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
+         char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114 */
 
          pos = png_safecat(message, (sizeof message), pos,
              png_format_number(number, number+(sizeof number),
              PNG_NUMBER_FORMAT_x, value));
-         pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
+         pos = png_safecat(message, (sizeof message), pos, "h: "); /* +2 = 116 */
       }
 #  endif
    /* The 'reason' is an arbitrary message, allow +79 maximum 195 */