Changes

[flang] Fix bugs in .mod file for abstract interface

When an abstract interface is defined, add the ABSTRACT attribute to
subprogram symbols that define the interface body. Make use of that
when writing .mod files to include "abstract" on the interface statement.

Also, fix a problem with the order of symbols in a .mod file. Sometimes
a name is mentioned before the "real" declaration, e.g. in an access
statement. We want the order to be based on the real definitions. In
these cases we replace the symbol name with an identical name with a
different source location. Then by sorting based on the source location
we get symbols in the right order.

Differential Revision: https://reviews.llvm.org/D93572

[MIRPrinter] Fix incorrect output of unnamed stack names

The MIRParser expects unnamed stack entries to have empty names ('').
In case of unnamed alloca instructions, the MIRPrinter would output
'<unnamed alloca>', which caused the MIRParser to reject the generated
code.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D93685

[InstCombine] 'hoist xor-by-constant from xor-by-value': ignore constantexprs

As it is being reported (in post-commit review) in
https://reviews.llvm.org/D93857
this fold (as i expected, but failed to come up with test coverage
despite trying) has issues with constant expressions.
Since we only care about true constants, which constantexprs are not,
don't perform such hoisting for constant expressions.

[TableGen] Fix bug in !interleave operator

I forgot to account for unresolved elements of the list.

Differential Revision: https://reviews.llvm.org/D93814

Revert "[benchmark] Fixed a build error when using CMake 3.15.1 + NDK-R20"

Temporairly revert until a consensus on post-commit comments is achieved.

This reverts commit a485a59d2172daaee1d5e734da54fbb243f7d54c.