Windows compatibility fixes

VS2013 has trouble with relative include paths for apps/openssl, so move
certhash_win/apps_win.c back to apps/openssl.

gmtime_r on mingw64 fails with negative time_t, override

gmtime_s fails all of the time unit tests, override

SHUT_RD/WR are defined in newer mingw64 headers, check before overriding

.gitignore

@@ -115,6 +115,8 @@ include/openssl/*.h
 /apps/nc/*.h
 /apps/nc/*.c
 /apps/nc/nc*
+!/apps/openssl/apps_win.c
+!/apps/openssl/certhash_win.c
 /apps/openssl/*.h
 /apps/openssl/*.c
 /apps/openssl/*.cnf