Fix llvm warnings on Mac

Patch from Scott Fleischman.  Warnings were:

harfbuzz/src/hb-font-private.hh:121:42: Implicit conversion loses
integer precision: 'long long' to 'hb_position_t' (aka 'int')
harfbuzz/src/hb-font-private.hh:126:42: Implicit conversion loses
integer precision: 'long long' to 'hb_position_t' (aka 'int')
harfbuzz/src/hb-font-private.hh:400:85: Implicit conversion loses
integer precision: 'long long' to 'hb_position_t' (aka 'int')
harfbuzz/src/hb-ot-layout-common-private.hh:1115:37: Implicit conversion
loses integer precision: 'long long' to 'int'
harfbuzz/src/hb-ft.cc:421:97: Implicit conversion loses integer
precision: 'unsigned long long' to 'int'
harfbuzz/src/hb-ft.cc:422:97: Implicit conversion loses integer
precision: 'unsigned long long' to 'int'

src/hb-ft.cc

diff --git a/src/hb-ft.cc b/src/hb-ft.cc
index 113b0eb..44e0b0b 100644
--- a/src/hb-ft.cc
+++ b/src/hb-ft.cc
@@ -418,8 +418,8 @@
 		     _hb_ft_get_font_funcs (),
 		     ft_face, (hb_destroy_func_t) _do_nothing);
   hb_font_set_scale (font,
-		     ((uint64_t) ft_face->size->metrics.x_scale * (uint64_t) ft_face->units_per_EM + (1<<15)) >> 16,
-		     ((uint64_t) ft_face->size->metrics.y_scale * (uint64_t) ft_face->units_per_EM + (1<<15)) >> 16);
+		     (int) (((uint64_t) ft_face->size->metrics.x_scale * (uint64_t) ft_face->units_per_EM + (1<<15)) >> 16),
+		     (int) (((uint64_t) ft_face->size->metrics.y_scale * (uint64_t) ft_face->units_per_EM + (1<<15)) >> 16));
   hb_font_set_ppem (font,
 		    ft_face->size->metrics.x_ppem,
 		    ft_face->size->metrics.y_ppem);