Mangle long and ulong correctly on 64-bit linux/osx
Merge pull request #3158 from yebblies/longmangle

[DDMD] Mangle C++ long and ulong correctly on 64-bit linux/osx
Fix Issue 11991 - Implicit catch picks up wrong 'Throwable'
Merge pull request #3147 from yebblies/issue11991

Issue 11991 - Implicit catch picks up wrong 'Throwable'
[Refactoring] clean up Dsymbol::semantic
fix Issue 12023 - template mixin fails within template class
Merge pull request #3174 from 9rnsr/fix12023

[REG2.065a] Issue 12023 - template mixin fails within template class