common_defs: remove workaround for old MSVC versions

MSVC supposedly supports stdbool.h since Visual Studio 2015
(https://docs.microsoft.com/en-us/cpp/overview/visual-cpp-language-conformance?view=msvc-160#c-standard-library-features-1).
The workaround that was being used is error-prone, so just remove it and
don't support VS versions older than VS2015 anymore.

common/common_defs.h

@@ -28,12 +28,12 @@
 #ifndef COMMON_COMMON_DEFS_H
 #define COMMON_COMMON_DEFS_H
 
-#ifndef _MSC_VER
-#  include <stdbool.h>
-#  include <stdlib.h>	/* for _byteswap_*() */
-#endif
+#include <stdbool.h>
 #include <stddef.h>	/* for size_t */
 #include <stdint.h>
+#ifndef _MSC_VER
+#  include <stdlib.h>	/* for _byteswap_*() */
+#endif
 #ifndef FREESTANDING
 #  include <string.h>	/* for memcpy() */
 #endif
@@ -52,19 +52,6 @@ typedef int16_t s16;
 typedef int32_t s32;
 typedef int64_t s64;
 
-/* bool */
-#ifdef _MSC_VER
- /*
-  * Old versions of MSVC (e.g. VS2010) don't have the C99 header stdbool.h.
-  * Beware: the below replacement isn't fully standard, since normally any value
-  * != 0 should be implicitly cast to a bool with value 1... but that doesn't
-  * happen if bool is really just an 'int'.
-  */
-   typedef int bool;
-#  define true	1
-#  define false	0
-#endif
-
 /* ssize_t, if not available in <sys/types.h> */
 #ifdef _MSC_VER
 #  ifdef _WIN64