gendef: Silence warnings about casting function pointers on GCC 8.

GCC 8 warns about casting between incompatible pointer to functions.
This can be worked around by casting the source pointer to an integer
type before to the destination pointer type.

Signed-off-by: Liu Hao <lh_mouse@126.com>

mingw-w64-tools/gendef/src/fsredir.c

diff --git a/mingw-w64-tools/gendef/src/fsredir.c b/mingw-w64-tools/gendef/src/fsredir.c
index a43dea3..d729a96 100644
--- a/mingw-w64-tools/gendef/src/fsredir.c
+++ b/mingw-w64-tools/gendef/src/fsredir.c
@@ -41,8 +41,8 @@
       fprintf(stderr, "kernel32.dll failed to load, failed to disable FS redirection.\n");
       return;
     }
-    redirectorfunction = (redirector)GetProcAddress(kernel32handle, "Wow64DisableWow64FsRedirection");
-    revertorfunction = (revertor)GetProcAddress(kernel32handle, "Wow64RevertWow64FsRedirection");
+    redirectorfunction = (redirector)(INT_PTR)GetProcAddress(kernel32handle, "Wow64DisableWow64FsRedirection");
+    revertorfunction = (revertor)(INT_PTR)GetProcAddress(kernel32handle, "Wow64RevertWow64FsRedirection");
     if (!redirectorfunction || ! revertorfunction) {
       FreeLibrary(kernel32handle);
       fprintf(stderr, "Wow64DisableWow64FsRedirection or Wow64RevertWow64FsRedirection functions missing.\n");