os: Adjust to support MSVC

- There is no S_IRUSR & friends  -> use _S_IREAD & co.
- Tthere is no sys_siglist       -> kind-of define it ourselves for all documented signals.

golang/os.cpp

@@ -37,7 +37,8 @@
 // GLIBC <  2.32 provides sys_siglist but not sigdescr_np in its headers
 // cut this short
 // (on darwing sys_siglist declaration is normally provided)
-#ifndef __APPLE__
+// (on windows sys_siglist is not available at all)
+#if !(defined(__APPLE__) || defined(_WIN32))
 extern "C" {
     extern const char * const sys_siglist[];
 }
@@ -286,8 +287,20 @@ string Signal::String() const {
     const Signal& sig = *this;
     const char *sigstr = nil;
 
+#ifdef _WIN32
+    switch (sig.signo) {
+    case SIGABRT:   return "Aborted";
+    case SIGBREAK:  return "Break";
+    case SIGFPE:    return "Floating point exception";
+    case SIGILL:    return "Illegal instruction";
+    case SIGINT:    return "Interrupt";
+    case SIGSEGV:   return "Segmentation fault";
+    case SIGTERM:   return "Terminated";
+    }
+#else
     if (0 <= sig.signo && sig.signo < NSIG)
         sigstr = ::sys_siglist[sig.signo]; // might be nil as well
+#endif
 
     if (sigstr != nil)
         return string(sigstr);

golang/os.h

@@ -95,9 +95,15 @@ private:
 
 // Open opens file @path.
 LIBGOLANG_API std::tuple<File, error> Open(const string &path, int flags = O_RDONLY,
-        mode_t mode = S_IRUSR | S_IWUSR | S_IXUSR |
+        mode_t mode =
+#if !defined(_MSC_VER)
+                      S_IRUSR | S_IWUSR | S_IXUSR |
                       S_IRGRP | S_IWGRP | S_IXGRP |
-                      S_IROTH | S_IWOTH | S_IXOTH);
+                      S_IROTH | S_IWOTH | S_IXOTH
+#else
+                      _S_IREAD | _S_IWRITE
+#endif
+        );
 
 // NewFile wraps OS-level file-descriptor into File.
 // The ownership of sysfd is transferred to File.