added header to macos for endian.h (#37)

Added header to macOS for endian.h

crypto/sig_picnic/macos_specific_endian.h

+#ifndef MACOS_SPECIFIC_ENDIAN_H
+#define MACOS_SPECIFIC_ENDIAN_H
+
+/** compatibility header for endian.h
+ * This is a simple compatibility shim to convert
+ * BSD/Linux endian macros to the Mac OS X equivalents.
+ * It is public domain.
+ * */
+
+#ifndef __APPLE__
+    #warning "This header file (endian.h) is MacOS X specific.\n"
+#endif	/* __APPLE__ */
+
+#include <machine/endian.h>
+#include <libkern/OSByteOrder.h>
+
+#define htobe16(x) OSSwapHostToBigInt16(x)
+#define htole16(x) OSSwapHostToLittleInt16(x)
+#define be16toh(x) OSSwapBigToHostInt16(x)
+#define le16toh(x) OSSwapLittleToHostInt16(x)
+
+#define htobe32(x) OSSwapHostToBigInt32(x)
+#define htole32(x) OSSwapHostToLittleInt32(x)
+#define be32toh(x) OSSwapBigToHostInt32(x)
+#define le32toh(x) OSSwapLittleToHostInt32(x)
+
+#define htobe64(x) OSSwapHostToBigInt64(x)
+#define htole64(x) OSSwapHostToLittleInt64(x)
+#define be64toh(x) OSSwapBigToHostInt64(x)
+#define le64toh(x) OSSwapLittleToHostInt64(x)
+
+#endif // MACOS_SPECIFIC_ENDIAN_H

crypto/sig_picnic/picnic_impl.c

@@ -20,6 +20,8 @@
 #if defined (__WIN32)
 	#include <Windows.h>
 	#include <bcrypt.h>
+#elif defined (__APPLE__)
+    #include "macos_specific_endian.h"
 #else
     #include <endian.h>
 #endif

crypto/sig_picnic/sig_picnic.pri

@@ -3,8 +3,9 @@ HEADERS += $$PWD/hash.h \
     $$PWD/picnic.h \
     $$PWD/picnic_impl.h \
     $$PWD/picnic_types.h \
-    $$PWD/platform.h \
+    $$PWD/platform.h
 
+macos { HEADERS += $$PWD/macos_specific_endian.h }
 
 SOURCES +=  $$PWD/hash.c \
     $$PWD/lowmc_constants.c \