Revert "Fix fatal error and the version flag option when compiling for windows"

This reverts commit f144f8a0b9.

depends/hosts/mingw32.mk

@@ -1,6 +1,6 @@
 mingw32_CC=x86_64-w64-mingw32-gcc-posix
 mingw32_CXX=x86_64-w64-mingw32-g++-posix
-mingw32_CFLAGS=-pipe -std=c++11
+mingw32_CFLAGS=-pipe -std=c11
 mingw32_CXXFLAGS=$(mingw32_CFLAGS) -std=c++11
 
 mingw32_release_CFLAGS=-O3

src/sync.cpp

@@ -25,13 +25,7 @@
 #include <boost/foreach.hpp>
 #include <boost/thread.hpp>
 
-#ifdef _WIN32
-#include <windows.h>
-#include <dbghelp.h>
-#else
-#include <execinfo.h>
-#endif
-
+#include <execinfo.h> /* backtrace, backtrace_symbols_fd */
 #include <unistd.h> /* STDOUT_FILENO */