fix Issue 12010 - Undefined template symbols for static library linked with debug symbols

Struct destructors and postblits will be stored in TypeInfo. So, partial semantic3 running for structs declared in non-root modules should also consider them.
Merge pull request #3165 from 9rnsr/fix12010

[REG2.065a] Issue 12010 - Undefined template symbols for static library linked with debug symbols
fix Issue 12016 - implicit immutable upcast becomes null in CTFE
Merge pull request #3168 from 9rnsr/fix12016

[REG2.065a] Issue 12016 - implicit immutable upcast becomes null in CTFE
fix Issue 12017 - DDoc leaves out the majority of documentation
Merge pull request #3169 from 9rnsr/fix12017

[REG2.065a] Issue 12017 - DDoc leaves out the majority of documentation