Fix Issue 10626 - ICE with vector operation

Fix regression by forwarding buildArrayIdent and buildArrayLoop to the base implementation for all other derived expressions.

Add test cases to improve coverage.
fix Issue 10768 - DMD does not show deprecation message for missing 'override' keyword

If a class/struct/template is not speculatively instantiated, error gagging should be ungagged temporarily during its semantic.
Use RAII idiom to do it reliably.
Improve bug4269 test cases
Fixed linker invocation when compiling dmd with visual studio and linker path has spaces
Merge pull request #2500 from Ingrater/mslinker

Fixed linker invocation when compiling dmd with visual studio
fix Issue 10398 - Dmd bugs detected by memcheck when compile druntime+phobos
Merge pull request #2502 from WalterBright/iasm-buf-overflow

fix Issue 10398 - Dmd bugs detected by memcheck when compile druntime+ph...
Merge pull request #2453 from 9rnsr/fix10768

Issue 10768 - DMD does not show deprecation message for missing 'override' keyword
Merge pull request #2345 from yebblies/issue10626

Fix Issue 10626 - ICE with vector operation