dub.compilers.ldc: Fix --rdmd with --compiler=ldc2 ...

Use two dashes to make rdmd ignore the option. ldc2 doesn't care.

Add support for '-platformlib' option. Fixes #2031 ...

This change adds the newly introduced LDC linker option '-platformlib'
to the isLinkeDFlag(...) function in ldc.d so the option to be passed to
LDC when invoked by DUB for linking.

Revert "Deduplicate dflags and lflags" (#2016) ...

PR #2016 introducted a de-duplication strategy that is too eager and corrupts argument chains, such as "-framework CoreServices -framework CoreFoundation" where the "-framework" argument needs to be duplicated for each framework.

This reverts commit 10bea6f.

Deduplicate dflags and lflags ...

For some reason, dflags and lflags were not using the 'add' convenience function,
which allows to deduplicate flags.
As a result some flags, especially link flags which propagate upwards,
ended up taking half of the command line length.

Replace occurences of 'in ref' with 'const scope ref' ...

In support for dlang/dmd#11000

Add architecture x86_omf for windows-dmd

ldc: support --arch=aarch64 and powerpc64 ...

Because Meson calls e.g. `dub describe something --arch aarch64`

gdc: Build dub_platform_probe with -fsyntax-only

LDC: Suppress noisy warning when cross-compiling via -arch=<triple>

LDC: Fix isLinkerDFlag() detection for options specified with 2 leading hyphens

Add support for iOS/tvOS/watchOS

Merge pull request #1823 from Geod24/fix1206 ...

Fix #1206: Remove warning when using ldmd2 or gdmd
merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>

Replace calls to NativePath.toString() with .name ...

This has been deprecated in vibe-core and only triggers with 'library-nonet'.

Fix #1206: Remove warning when using ldmd2 or gdmd ...

This warning is being triggered frequently when ldmd2 or gdmd
(dmd-like CLI interface for ldc2 and gdc, respectively)
are used as '--compiler' argument.
They were introduced at the same time as the platform probe
(8ac4848),
probably for defensive programming, but have not proved useful.

reduce visual complexity of concatenation with std.string.fromat

Print the platform probe atomically ...

DMD may print some stuff in between call of `pragma(msg)` and corrupt the json data.

[dip1000] Fix compilation and test it on Travis CI

Fix linking shared libs with ldmd2 and gdmd

Improve cross-compilation support (replace `version` checks by BuildPlatform runtime checks) ...

Also fixes #1249. For LDC as implicit cross compiler, the file
extensions for libraries and object files etc. don't depend on the
compiler, but solely on the target. Targets selected with `--arch` are
correctly probed by dub, so that the parsed `BuildPlatform` represents
the target platform.

ldc2: Only use `-L--no-as-needed` for Linux *targets*

ldc2: Fix MSVC target detection for static libs ...

With --arch, the build (target) platform might now diverge from the host
platform. The compiler's default triple doesn't matter when
cross-compiling, so use the <name>.lib MSVC format when targeting Windows
but not MinGW.

This fixes one aspect of #1599.

Enable specifying full target triples as --arch for ldc2 ...

By treating all 'architectures' containing a `-` as `-mtriple` values.
E.g., `dub --arch=wasm32-unknown-unknown-wasm` to cross-compile to
WebAssembly. This dub switch is already used when probing the compiler,
so the build platform detection works as expected.

Also add `wasm` as detected platform and use the .wasm executable file
extension (for ldc2).

This fixes #1749 when moving the `-mtriple` option from the dub config
file to the dub command line.

Support separate linking with ldc2 ...

This is basically #1548 with an augmented set of compiler flags being
included in the linking command lines.

Restrict extra ldc2 invocation for static libs to Windows hosts ...

Don't perform the does-default-target-triple-contain-msvc check on
non-Windows hosts (which would need a hacked LLVM to return true on
other hosts).

Support a few more ldc2 command-line options

`alias Nullable.get this` will soon be deprecated. Use `.get`.

fix #1003 - Check empty ldflags

Use -dumpfullversion to determine GDC version

Windows: Don't use Optlink by default (#1661) ...

Windows: Don't use Optlink by default
merged-on-behalf-of: Sebastian Wilzbach <sebi.wilzbach@gmail.com>

Perform the tool chain checks based on the compiler name. ...

Gets rid of the additional methods in the Compiler interface and moves the checks to a more central location, since other generators apart from BuildGenerator might want to perform the checks in the future. Also keeps the API "package" for now to avoid adding insufficiently though-out public APIs.