[libpng15] Constant changes for 64-bit compatibility (removal of L suffixes).

The 16-bit cases still use "L" as we don't have a 16-bit test system.
diff --git a/pngset.c b/pngset.c
index 79968d3..373d21b 100644
--- a/pngset.c
+++ b/pngset.c
@@ -602,10 +602,10 @@
 #  ifdef PNG_cHRM_SUPPORTED
    png_set_cHRM_fixed(png_ptr, info_ptr,
       /* color      x       y */
-      /* white */ 31270L, 32900L,
-      /* red   */ 64000L, 33000L,
-      /* green */ 30000L, 60000L,
-      /* blue  */ 15000L,  6000L
+      /* white */ 31270, 32900,
+      /* red   */ 64000, 33000,
+      /* green */ 30000, 60000,
+      /* blue  */ 15000,  6000
    );
 #  endif /* cHRM */
 }