[smooth] Fix compilation for x86_32.x86 ABI

The code assumed that if __SSE2__ is defined, then 64-bit
integer types are available. This is not the case apparently
for certain multilib compiler targets like x86_32.x86 used
by Gentoo.

This patch fixes the issue by disabling the special code
path when 64-bit integer types are not available.

https://gitlab.freedesktop.org/freetype/freetype/-/issues/1071

src/smooth/ftgrays.c

@@ -1018,6 +1018,16 @@ typedef ptrdiff_t  FT_PtrDist;
 #  define BEZIER_USE_DDA  0
 #endif
 
+/* For now, the code that depends on BEZIER_USE_DDA requires
+ * FT_Int64 to be defined. If FT_LONG64 is not defined, meaning
+ * there is no 64-bit type available, disable it to avoid
+ * compilation errors. See for example
+ * https://gitlab.freedesktop.org/freetype/freetype/-/issues/1071
+ */
+#if !defined(FT_LONG64)
+#  undef BEZIER_USE_DDA
+#  define BEZIER_USE_DDA  0
+#endif
 
 #if BEZIER_USE_DDA