Fix: Drop foreign key for avoid Mysql crash

htdocs/install/mysql/migration/3.6.0-3.7.0.sql

@@ -208,10 +208,14 @@ UPDATE llx_product SET fk_barcode_type = NULL WHERE fk_barcode_type NOT IN (SELE
 ALTER TABLE  llx_product_price ADD INDEX idx_product_price_fk_user_author (fk_user_author);
 UPDATE llx_product_price set fk_user_author = null where fk_user_author = 0;
 UPDATE llx_product_price set fk_user_author = null where fk_user_author not in (select rowid from llx_user);
+-- drop foreign key for avoid a mysql crash
+ALTER TABLE  llx_product_price DROP FOREIGN KEY fk_product_price_user_author;
 ALTER TABLE  llx_product_price ADD CONSTRAINT fk_product_price_user_author FOREIGN KEY (fk_user_author) REFERENCES  llx_user (rowid);
 -- fk_product
 ALTER TABLE  llx_product_price ADD INDEX idx_product_price_fk_product (fk_product);
 DELETE from llx_product_price where fk_product NOT IN (SELECT rowid from llx_product);
+-- drop foreign key for avoid a mysql crash
+ALTER TABLE  llx_product_price DROP FOREIGN KEY fk_product_price_product;
 ALTER TABLE  llx_product_price ADD CONSTRAINT fk_product_price_product FOREIGN KEY (fk_product) REFERENCES  llx_product (rowid);
 
 ALTER TABLE llx_commande_fournisseur MODIFY COLUMN date_livraison datetime;