Fix the warnings when compiling harfbuzz with clang in Android

third_party/harfbuzz/contrib/harfbuzz-freetype.c

 #include <stdint.h>
 
 #include <ft2build.h>
 #include FT_FREETYPE_H
 #include FT_TRUETYPE_TABLES_H
 
 #if 0
 #include <freetype/freetype.h>
 #include <freetype/tttables.h>
 #endif
 
 #include <harfbuzz-shaper.h>
 #include "harfbuzz-unicode.h"
 
 static HB_Bool
 hb_freetype_string_to_glyphs(HB_Font font,
                              const HB_UChar16 *chars, hb_uint32 len,
                              HB_Glyph *glyphs, hb_uint32 *numGlyphs,
                              HB_Bool is_rtl) {
   FT_Face face = (FT_Face) font->userData;
   if (len > *numGlyphs)
     return 0;
 
-  size_t i = 0, j = 0;
+  ssize_t i = 0;
+  hb_uint32 j = 0;
   while (i < len) {
     const uint32_t cp = utf16_to_code_point(chars, len, &i);
     glyphs[j++] = FT_Get_Char_Index(face, cp);
   }
 
   *numGlyphs = j;
 
   return 1;
 }
 
@@ skipping 11 matching lines @@
     }
 
     advances[i] = face->glyph->advance.x;
   }
 }
 
 static HB_Bool
 hb_freetype_can_render(HB_Font font, const HB_UChar16 *chars, hb_uint32 len) {
   FT_Face face = (FT_Face)font->userData;
 
-  size_t i = 0;
+  ssize_t i = 0;
   while (i < len) {
     const uint32_t cp = utf16_to_code_point(chars, len, &i);
     if (FT_Get_Char_Index(face, cp) == 0)
       return 0;
   }
 
   return 1;
 }
 
 static HB_Error
@@ skipping 73 matching lines @@
   FT_Face face = (FT_Face) voidface;
   FT_ULong ftlen = *len;
 
   if (!FT_IS_SFNT(face))
     return HB_Err_Invalid_Argument;
 
   const FT_Error error = FT_Load_Sfnt_Table(face, tag, 0, buffer, &ftlen);
   *len = ftlen;
   return (HB_Error) error;
 }