Fix build on Windows with recent versions of MSVC

- vsnprintf and snprintf are available since vs2015
- define ISREG if not provided
- guard unistd.h include with HAVE_UNISTD_H
- isnan() is available after vs2010

src/cairo-compiler-private.h

@@ -201,10 +201,12 @@
 #define hypot _hypot
 #define pclose _pclose
 #define popen _popen
-#define snprintf _snprintf
 #define strdup _strdup
 #define unlink _unlink
-#define vsnprintf _vsnprintf
+#if _MSC_VER < 1900
+  #define vsnprintf _vsnprintf
+  #define snprintf _snprintf
+#endif
 #endif
 
 #ifdef _MSC_VER

test/bitmap-font.c

@@ -27,7 +27,9 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#ifdef HAVE_UNISTD_H
 #include <unistd.h>
+#endif
 
 #include <cairo-ft.h>
 #include <fontconfig/fontconfig.h>
@@ -73,6 +75,10 @@ check_font_extents (const cairo_test_context_t *ctx, cairo_t *cr, const char *co
     return CAIRO_TEST_SUCCESS;
 }
 
+#if !defined(S_ISREG) && defined(S_IFMT) && defined(S_IFREG)
+#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
+#endif
+
 static cairo_test_status_t
 draw (cairo_t *cr, int width, int height)
 {

test/cairo-test.h

@@ -58,7 +58,9 @@ typedef unsigned __int64 uint64_t;
 #define _USE_MATH_DEFINES
 
 #include <float.h>
+#if _MSC_VER <= 1600
 #define isnan(x) _isnan(x)
+#endif
 
 #endif