Avoid parsing `-mllvm*` command-line options if there aren't any

LLD somehow uses a different global LLVM command-line parser than LDC,
one with no registered options, so parsing is guaranteed to fail, even
if there are no args.
[It's only needed for LTO codegen options anyway.]

Merge remote-tracking branch 'upstream/release_80' into ldc-release_80

Merge remote-tracking branch 'upstream/release_70' into ldc-release_70

Avoid parsing `-mllvm*` command-line options if there aren't any

LLD somehow uses a different global LLVM command-line parser than LDC,
one with no registered options, so parsing is guaranteed to fail, even
if there are no args.
[It's only needed for LTO codegen options anyway.]

WebAssembly: Avoid parsing `-mllvm*` command-line options if there ar…

…en't any

Merge remote-tracking branch 'upstream/release_60' into ldc-release_60

Avoid parsing `-mllvm*` command-line options if there aren't any

LLD somehow uses a different global LLVM command-line parser than LDC,
one with no registered options, so parsing is guaranteed to fail, even
if there are no args.
[It's only needed for LTO codegen options anyway.]

Merge remote-tracking branch 'upstream/release_50' into ldc-release_50

Avoid parsing `-mllvm*` command-line options if there aren't any

LLD somehow uses a different global LLVM command-line parser than LDC,
one with no registered options, so parsing is guaranteed to fail, even
if there are no args.
[It's only needed for LTO codegen options anyway.]