Fix missing and conditional includes, #warning on MSVC

c++/src/capnp/compiler/parser.c++

@@ -23,7 +23,9 @@
 #include "md5.h"
 #include <capnp/dynamic.h>
 #include <kj/debug.h>
+#if !_MSC_VER
 #include <unistd.h>
+#endif
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>

c++/src/capnp/endian.h

@@ -185,9 +185,14 @@ using WireValue = SwappingWireValue<T>;
 // Unknown endianness.  Fall back to bit shifts.
 
 #if !CAPNP_DISABLE_ENDIAN_DETECTION
+#if _MSC_VER
+#pragma message("Couldn't detect endianness of your platform.  Using unoptimized fallback implementation.")
+#pragma message("Consider changing this code to detect your platform and send us a patch!")
+#else
 #warning "Couldn't detect endianness of your platform.  Using unoptimized fallback implementation."
 #warning "Consider changing this code to detect your platform and send us a patch!"
 #endif
+#endif  // !CAPNP_DISABLE_ENDIAN_DETECTION
 
 template <typename T, size_t size = sizeof(T)>
 class ShiftingWireValue;

c++/src/capnp/rpc.c++

@@ -26,6 +26,7 @@
 #include <kj/async.h>
 #include <kj/one-of.h>
 #include <kj/function.h>
+#include <functional>  // std::greater
 #include <unordered_map>
 #include <map>
 #include <queue>