Enable speed on win32

- Use thread and sleep instead of signal and alarm, on win32
- Disable -multi option on win32 since fork is hard to implement

m4/check-os-options.m4

@@ -107,7 +107,7 @@ char buf[1]; getentropy(buf, 1);
 		CPPFLAGS="$CPPFLAGS -D_GNU_SOURCE -D_POSIX -D_POSIX_SOURCE -D__USE_MINGW_ANSI_STDIO"
 		CPPFLAGS="$CPPFLAGS -D_REENTRANT -D_POSIX_THREAD_SAFE_FUNCTIONS"
 		CPPFLAGS="$CPPFLAGS -DWIN32_LEAN_AND_MEAN -D_WIN32_WINNT=0x0600"
-		CPPFLAGS="$CPPFLAGS -DOPENSSL_NO_SPEED"
+		CPPFLAGS="$CPPFLAGS"
 		AC_SUBST([PLATFORM_LDADD], ['-lws2_32'])
 		;;
 	*solaris*)