fix Issue 10056 - Strange Error with templates and string.format

If IFTI error is gagged (`(flags&1) != 0` in deduceTemplateFunction), function body semantic should be delayed, as same as `FuncDeclaration::overloadResolve` do.

For the lazily function semantic, hasIdentity(Assign|Equals) should not allocate arguments `Expressions` on stack.
Merge pull request #2013 from 9rnsr/fix10056

[REG2.063a] Issue 10056 - Strange Error with templates and string.format