fix Issue 9990 - templates with function alias cause forward reference error
fix Issue 9993 - const ctor should be preferred than mutable for const obj creation
fix Issue 9931 - Mac OS X ABI not followed when returning structs for extern (C)
fix Issue 9994 - Built-in generated opAssign should call dtor on assignment
Merge pull request #1938 from WalterBright/fix9931

fix Issue 9931 - Mac OS X ABI not followed when returning structs for extern (C)
Merge pull request #1941 from 9rnsr/fix9994

Issue 9994 - Built-in generated opAssign should call dtor on assignment
Merge pull request #1936 from 9rnsr/fix9990

Issue 9990 - templates with function alias cause forward reference error
Merge pull request #1939 from 9rnsr/fix9993

Issue 9993 - const ctor should be preferred than mutable for const obj creation