Changes

[LIBOMPTARGET]FIX define declaration, NFC

Fixed declaration of define by adding a comma symbol. Required to fix build without profiling.

[JITLink][ELF/x86-64] When building PLT stub, use -4 offset for PCRel32.

This is required for ELF where PCRel32 doesn't implicitly subtract 4.

No test case yet: I haven't figured out a good way to test stub
generation -- this may required extensions to jitlink-check.

[ORC] Fix debug logging message.

Remove requirement for -maltivec to be used when using -mabi=vec-extabi or -mabi=vec-default when not using vector code

The previous implementation required that `-maltivec` be specified when using either `-mabi=vec-extabi` or `-mabi=vec-default`, this patch removes that requirement.

Reviewed By: cebowleratibm

Differential Revision: https://reviews.llvm.org/D94986

Revert "[flang] Search for #include "file" in right directory"

This reverts commit d987b61b1dce9948801ac37704477e7c257100b1.

As pointed out in https://reviews.llvm.org/D95388, the reverted commit
causes build failures in the following Flang buildbots:
  * http://lab.llvm.org:8011/#/builders/32/builds/2642
  * http://lab.llvm.org:8011/#/builders/33/builds/2131
  * http://lab.llvm.org:8011/#/builders/135/builds/1473
  * http://lab.llvm.org:8011/#/builders/66/builds/1559
  * http://lab.llvm.org:8011/#/builders/134/builds/1409
  * http://lab.llvm.org:8011/#/builders/132/builds/1817
I'm guessing that the patch was only tested with
`FLANG_BUILD_NEW_DRIVER=Off` (i.e. the default). The builders listed
above set `FLANG_BUILD_NEW_DRIVER` to `On`.

Although fixing the build is relatively easy, the reverted patch
modifies the behaviour of the frontend, which breaks driver tests. In
particular, in https://reviews.llvm.org/D93453 support for `-I` was
added that depends on the current behaviour. The reverted patch
changes that behaviour. Either the tests have to be updated or the
change fine-tuned.

[ORC] Attempt to auto-claim responsibility for weak defs in ObjectLinkingLayer.

Compilers may insert new definitions during compilation, E.g. EH personality
function pointers, or named constant pool entries. This commit causes
ObjectLinkingLayer to attempt to claim responsibility for all weak definitions
in objects as they're linked. This is always safe (first claimant for each
symbol is granted responsibility, subsequent claims are rejected without error)
and prevents compiler-injected symbols from being dead-stripped (which they
will be if they remain unclaimed by anyone).

This change was motivated by errors seen by an out-of-tree client while testing
eh-frame support in JITLink ELF/x86-64: IR containing exceptions didn't define
DW.ref.__gxx_personality_v0 (since it's added by CodeGen), and this caused
DW.ref.__gxx_personality_v0 to be dead-stripped leading to linker failures.

No test case yet: We won't have a way to test in-tree until we enable JITLink
for lli on Linux.