implement --dynamic-linker <argument> override option

[emaste]

Bugzilla Link	23233
Resolution	FIXED
Resolved on	Apr 19, 2015 19:18
Version	unspecified
OS	FreeBSD
Blocks	#23588

Extended Description

Required for the FreeBSD base system build.

GNU ld description:
--dynamic-linker file
Set the name of the dynamic linker. This is only meaningful when
generating dynamically linked ELF executables. The default dynamic
linker is normally correct; don't use this unless you know what you
are doing.

[llvmbot]

A quick scan of the code shows up this is already implemented in HEAD, is it failing for you in some way?

[emaste]

Failing command line is:

/tank/emaste/src/freebsd/tools_bin/ld -Bdynamic -T /tank/emaste/src/freebsd/sys/conf/ldscript.amd64 --no-warn-mismatch --warn-common --export-dynamic --dynamic-linker /red/herring -o kernel.debug -X locore.o cam.o cam_compat.o ...

It seems -dynamic-linker works, but --dynamic-linker (two dashes) does not.

[llvmbot]

r235282.

[emaste]

Update title based on fix: the form is --dynamic-linker /red/herring in the FreeBSD build; --dynamic-linker=/red/herring and -dynamic-linker /red/herring were already supported, but -- and no = was not.