common : remove unnecessary includes (#947)

examples/common.cpp

@@ -7,12 +7,6 @@
 #include <iterator>
 #include <algorithm>
 
-#if defined(_MSC_VER) || defined(__MINGW32__)
-#include <malloc.h> // using malloc.h with MSC/MINGW
-#elif !defined(__FreeBSD__) && !defined(__NetBSD__) && !defined(__OpenBSD__)
-#include <alloca.h>
-#endif
-
 #if defined (_WIN32)
 #include <fcntl.h>
 #include <io.h>