Fix MSVC warning C4018 for sqlite.

third_party/sqlite/patches/0006-Virtual-table-supporting-recovery-of-corrupted-datab.patch

Index: third_party/sqlite/patches/0006-Virtual-table-supporting-recovery-of-corrupted-datab.patch
diff --git a/third_party/sqlite/patches/0006-Virtual-table-supporting-recovery-of-corrupted-datab.patch b/third_party/sqlite/patches/0006-Virtual-table-supporting-recovery-of-corrupted-datab.patch
index 24fcbcf6759996d5b14a9dcd70cb8fe042195369..eb1cffa5b6d566a5effe75be2bbaa889b6c9f939 100644
--- a/third_party/sqlite/patches/0006-Virtual-table-supporting-recovery-of-corrupted-datab.patch
+++ b/third_party/sqlite/patches/0006-Virtual-table-supporting-recovery-of-corrupted-datab.patch
@@ -1891,7 +1891,7 @@ index 0000000..c996d53
 +
 +  FNENTRY();
 +
-+  if( i>=pRecover->nCols ){
++  if( (unsigned)i>=pRecover->nCols ){
 +    return SQLITE_ERROR;
 +  }
 +
@@ -2198,11 +2198,11 @@ index 0000000..c996d53
 +  sqlite3_vtab **ppVtab,              /* OUT: New virtual table */
 +  char **pzErr                        /* OUT: Error message, if any */
 +){
-+  const unsigned kTypeCol = 4;  /* First argument with column type info. */
-+  Recover *pRecover;            /* Virtual table structure being created. */
-+  char *zDot;                   /* Any dot found in "db.table" backing. */
-+  u32 iRootPage;                /* Root page of backing table. */
-+  char *zCreateSql;             /* Schema of created virtual table. */
++  const int kTypeCol = 4;  /* First argument with column type info. */
++  Recover *pRecover;       /* Virtual table structure being created. */
++  char *zDot;              /* Any dot found in "db.table" backing. */
++  u32 iRootPage;           /* Root page of backing table. */
++  char *zCreateSql;        /* Schema of created virtual table. */
 +  int rc;
 +
 +  /* Require to be in the temp database. */