No need for stdint.h and unistd.h when building with MSVC

MSVC 2008 and lower did not provide stdint.h and unistd.h.
This patch adjusts gif.pri, accordingly. We typedef uint32_t
ourselves in gif_hash.h.

http://code.google.com/p/phantomjs/issues/detail?id=424

src/gif/gif.pri

@@ -2,10 +2,12 @@ VPATH += $$PWD
 INCLUDEPATH += $$PWD
 
 DEFINES += HAVE_CONFIG_H
-DEFINES += HAVE_STDINT_H
 DEFINES += HAVE_FCNTL_H
-DEFINES += HAVE_UNISTD_H
 DEFINES += HAVE_STDARG_H
+!win32-msvc* {
+    DEFINES += HAVE_STDINT_H
+    DEFINES += HAVE_UNISTD_H
+}
 
 SOURCES += gif_err.c
 SOURCES += gifalloc.c

src/gif/gif_hash.h

@@ -17,6 +17,8 @@
 /* Find a thirty-two bit int type */
 #ifdef HAVE_STDINT_H
 #include <stdint.h>
+#else if defined(Q_CC_MSVC)
+typedef unsigned __int32 uint32_t;
 #endif
 #ifdef HAVE_INTTYPES_H
 #include <inttypes.h>