gallium/util: use #pragma section instead of #pragma data_seg

They apparently both declare the section, but #pragma data_seg
also puts all subsequent definitions in the section, which is
undesirable.

This should be the correct solution, and is actually used by the
reference I cited (but I forgot to do it in my code).

Untested, let me know if it doesn't work.

src/gallium/auxiliary/util/u_init.h

@@ -40,7 +40,7 @@
 /* add a pointer to the section where MSVC stores global constructor pointers */
 /* see http://blogs.msdn.com/vcblog/archive/2006/10/20/crt-initialization.aspx and
    http://stackoverflow.com/questions/1113409/attribute-constructor-equivalent-in-vc */
-#pragma data_seg(".CRT$XCU")
+#pragma section(".CRT$XCU",read)
 #define UTIL_INIT(f) static void __cdecl f##__init(void) {f();}; __declspec(allocate(".CRT$XCU")) void (__cdecl* f##__xcu)(void) = f##__init;
 #elif defined(__GNUC__)
 #define UTIL_INIT(f) static void f##__init(void) __attribute__((constructor)); static void f##__init(void) {f();}