Added 'ps_buffer_stmt_read_all_rows' patch for libmariadb

This patch handles local variable invalidation in 'mthd_stmt_read_all_rows'
due to stack swapping because of the use of 'ma_free_root' over 'stmt'
buffer.

deps/Makefile

@@ -187,6 +187,7 @@ mariadb-client-library/mariadb_client/libmariadb/libmariadbclient.a: libssl/open
 	cd mariadb-client-library/mariadb_client && patch unittest/libmariadb/basic-t.c < ../unittest_basic-t.c.patch
 	cd mariadb-client-library/mariadb_client && patch unittest/libmariadb/charset.c < ../unittest_charset.c.patch
 	cd mariadb-client-library/mariadb_client && patch -p0 < ../client_deprecate_eof.patch
+	cd mariadb-client-library/mariadb_client && patch -p0 < ../ps_buffer_stmt_read_all_rows.patch
 	cd mariadb-client-library/mariadb_client && CC=${CC} CXX=${CXX} ${MAKE} mariadbclient
 # cd mariadb-client-library/mariadb_client/include && make my_config.h
 

deps/mariadb-client-library/ps_buffer_stmt_read_all_rows.patch

@@ -0,0 +1,29 @@
+diff --git libmariadb/mariadb_stmt.c libmariadb/mariadb_stmt.c
+index bbc2831..e66d810 100644
+--- libmariadb/mariadb_stmt.c
++++ libmariadb/mariadb_stmt.c
+@@ -207,6 +207,24 @@ int mthd_stmt_read_all_rows(MYSQL_STMT *stmt)
+ 
+   while ((packet_len = ma_net_safe_read(stmt->mysql, &is_data_packet)) != packet_error)
+   {
++    // This change is required due to the new algorithm introduced in ProxySQL in #3295.
++    // ********************************************************************************
++    // DETAILS:
++    // Since #3295 ProxySQL performs a buffering on the resulset received by a prepared
++    // statement. This way ProxySQL doesn't require to retain the whole result of the
++    // prepared statement in memory. For this purpose it's required to free the memory
++    // allocated in 'MYSQL_STMT' via 'ma_free_root'. Because of this, local pointers
++    // within this function pointing to the result data gets invalidated due to stack
++    // swapping. Reinitializing then to the current values pointing to the new allocated
++    // memory for 'MYSQL_STMT' is required. Since this only happens when we force
++    // 'stmt->result.rows' to be '1', it's the only case in which these variables
++    // need a reset.
++    if (stmt->result.rows == 1) {
++      result= &stmt->result;
++      pprevious= &result->data->next;
++    }
++    // ********************************************************************************
++
+     p= stmt->mysql->net.read_pos;
+     // The check is by 'ma_net_safe_read'
+     if (p[0] == 0 || is_data_packet)