Bootstrap failure on 64bit Windows

[Andy Moreton]

Bootstrapping a 64bit Windows build (msys2 mingw64) failed this morning:

    dumped_data_commit: memory exhausted.
    Enlarge dumped_data[]!

The following patch fixes this:

diff --git a/src/w32heap.c b/src/w32heap.c
index 47ffec1c3038..ec5b04119bfd 100644
--- a/src/w32heap.c
+++ b/src/w32heap.c
@@ -115,7 +115,7 @@ typedef struct _RTL_HEAP_PARAMETERS {
    to build only the first bootstrap-emacs.exe with the large size,
    and reset that to a lower value afterwards.  */
 #if defined _WIN64 || defined WIDE_EMACS_INT
-# define DUMPED_HEAP_SIZE (19*1024*1024)
+# define DUMPED_HEAP_SIZE (20*1024*1024)
 #else
 # define DUMPED_HEAP_SIZE (12*1024*1024)
 #endif

Bootstrapping a 32bit windows build (msys mingw) is ok with the original
size.

    AndyM