MSVC: Define inline and restrict. #3237

MSVC 2015 defines __func__ (C++11).
    https://msdn.microsoft.com/en-us/library/dn919276.aspx

MSVC only allows inline in C++ and requires __inline in C instead.
    https://msdn.microsoft.com/en-us/library/bw1hbe6y.aspx

src/nvim/os/win_defs.h

@@ -21,6 +21,15 @@
 // - SYS_VIMRC_FILE
 // - SPECIAL_WILDCHAR
 
+#ifdef _MSC_VER
+# ifndef inline
+#  define inline __inline
+# endif
+# ifndef restrict
+#  define restrict __restrict
+# endif
+#endif
+
 typedef SSIZE_T ssize_t;
 
 #ifndef SSIZE_MAX