The Senate voted 93 to 0 to appropriate $8.5 billion for military construction projects, including the first major spending for six new Navy ports in the Gulf of Mexico. The measure was sent to a House-Senate conference to be reconciled with the $8.3-billion version the House passed July 17, 371 to 48. President Reagan had sought $10.1 billion for Pentagon construction for the fiscal year that began Oct. 1. But the House and Senate voted to reduce that request as part of the effort to cut federal spending and shrink the deficit. The Senate measure includes the entire $242 million requested for the new ports to berth ships for a larger fleet, but the House version proposes $172 million.