Add mingw32 support

With these changes, on Ubuntu I can do:

./configure --host=i586-mingw32msvc  && make

configure.ac

@@ -104,6 +104,7 @@ dnl ==========================================================================
 
 PKG_CHECK_MODULES(ICU, icu, have_icu=true, [
 	AC_CHECK_PROG([have_icu], [icu-config], [true], [false])
+	have_icu=false
 	if $have_icu; then
 		icu_cflags=`icu-config --cppflags`
 		icu_libs=`icu-config --ldflags-libsonly`

src/hb-mutex-private.hh

@@ -53,9 +53,9 @@ typedef GStaticMutex hb_mutex_impl_t;
 #define hb_mutex_impl_free(M)	g_static_mutex_free (M)
 
 
-#elif defined(_MSC_VER)
+#elif defined(_MSC_VER) || defined(__MINGW32__)
 
-#include <Windows.h>
+#include <windows.h>
 
 typedef CRITICAL_SECTION hb_mutex_impl_t;
 #define HB_MUTEX_IMPL_INIT	{ NULL, 0, 0, NULL, NULL, 0 }

src/hb-open-type-private.hh

@@ -384,6 +384,11 @@ struct IntType
   DEFINE_SIZE_STATIC (sizeof (Type));
 };
 
+/* Typedef these to avoid clash with windows.h */
+#define USHORT	HB_USHORT
+#define SHORT	HB_SHORT
+#define ULONG	HB_ULONG
+#define LONG	HB_LONG
 typedef IntType<uint16_t> USHORT;	/* 16-bit unsigned integer. */
 typedef IntType<int16_t>  SHORT;	/* 16-bit signed integer. */
 typedef IntType<uint32_t> ULONG;	/* 32-bit unsigned integer. */

src/hb-private.hh

@@ -139,7 +139,11 @@ ASSERT_STATIC (sizeof (hb_var_int_t) == 4);
 #endif
 
 #ifndef HB_INTERNAL
-# define HB_INTERNAL __attribute__((__visibility__("hidden")))
+# ifndef __MINGW32__
+#  define HB_INTERNAL __attribute__((__visibility__("hidden")))
+# else
+#  define HB_INTERNAL
+# endif
 #endif
 
 

src/main.cc

@@ -25,6 +25,7 @@
  */
 
 #define HB_OT_LAYOUT_CC
+#include "hb-mutex-private.hh"
 #include "hb-open-file-private.hh"
 #include "hb-ot-layout-gdef-private.hh"
 #include "hb-ot-layout-gsubgpos-private.hh"