[sql] Import SQLite 3.17.0.

third_party/sqlite/src/ext/fts5/fts5_unicode2.c

Index: third_party/sqlite/src/ext/fts5/fts5_unicode2.c
diff --git a/third_party/sqlite/src/ext/fts5/fts5_unicode2.c b/third_party/sqlite/src/ext/fts5/fts5_unicode2.c
index 8ad709d0fd6b4528f9e2b94bf326b361386fa136..1ef56f61567cc72934b32113546f4d9f4c2d17d2 100644
--- a/third_party/sqlite/src/ext/fts5/fts5_unicode2.c
+++ b/third_party/sqlite/src/ext/fts5/fts5_unicode2.c
@@ -125,9 +125,9 @@ int sqlite3Fts5UnicodeIsalnum(int c){
     0xFFFFFFFF, 0xFC00FFFF, 0xF8000001, 0xF8000001,
   };
 
-  if( c<128 ){
+  if( (unsigned int)c<128 ){
     return ( (aAscii[c >> 5] & (1 << (c & 0x001F)))==0 );
-  }else if( c<(1<<22) ){
+  }else if( (unsigned int)c<(1<<22) ){
     unsigned int key = (((unsigned int)c)<<10) | 0x000003FF;
     int iRes = 0;
     int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;