Merge pull request #2735 from xmcclure/early-lookup-addr

Early ICALL_ADDR lookup on pinvoke to fix checked-build assert

The pinvoke implementation in the failure case was creating a managed
exception object while in blocking mode, a rules violation. This patch
puts a redundant lookup early so that any exceptions occur before
blocking mode is entered. (The "real" lookup is unchanged because the
current pattern is optimized well by the JIT.)