Fix the max_page_count pragma so that it will not set to a value smaller

than the current database size, as the documentation requires.  Also,
remove all occurances of atoi() from the core.

FossilOrigin-Name: 2031974b606ef713b5f34522b2221470d98687c5

src/util.c

@@ -541,6 +541,16 @@ int sqlite3GetInt32(const char *zNum, int *pValue){
   return 1;
 }
 
+/*
+** Return a 32-bit integer value extracted from a string.  If the
+** string is not an integer, just return 0.
+*/
+int sqlite3Atoi(const char *z){
+  int x = 0;
+  if( z ) sqlite3GetInt32(z, &x);
+  return x;
+}
+
 /*
 ** The variable-length integer encoding is as follows:
 **