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-font-private.hh

diff --git a/src/hb-font-private.hh b/src/hb-font-private.hh
index 00c0cc3..aa6c515 100644
--- a/src/hb-font-private.hh
+++ b/src/hb-font-private.hh
@@ -118,12 +118,12 @@
   /* Convert from parent-font user-space to our user-space */
   inline hb_position_t parent_scale_x_distance (hb_position_t v) {
     if (unlikely (parent && parent->x_scale != x_scale))
-      return v * (int64_t) this->x_scale / this->parent->x_scale;
+      return (hb_position_t) (v * (int64_t) this->x_scale / this->parent->x_scale);
     return v;
   }
   inline hb_position_t parent_scale_y_distance (hb_position_t v) {
     if (unlikely (parent && parent->y_scale != y_scale))
-      return v * (int64_t) this->y_scale / this->parent->y_scale;
+      return (hb_position_t) (v * (int64_t) this->y_scale / this->parent->y_scale);
     return v;
   }
   inline hb_position_t parent_scale_x_position (hb_position_t v) {
@@ -397,7 +397,7 @@
   }
 
   private:
-  inline hb_position_t em_scale (int16_t v, int scale) { return v * (int64_t) scale / face->get_upem (); }
+  inline hb_position_t em_scale (int16_t v, int scale) { return (hb_position_t) (v * (int64_t) scale / face->get_upem ()); }
 };
 
 #define HB_SHAPER_DATA_CREATE_FUNC_EXTRA_ARGS

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);

src/hb-ot-layout-common-private.hh

diff --git a/src/hb-ot-layout-common-private.hh b/src/hb-ot-layout-common-private.hh
index 1e75930..367db95 100644
--- a/src/hb-ot-layout-common-private.hh
+++ b/src/hb-ot-layout-common-private.hh
@@ -1112,7 +1112,7 @@
 
     if (!pixels) return 0;
 
-    return pixels * (int64_t) scale / ppem;
+    return (int) (pixels * (int64_t) scale / ppem);
   }