tests: support DC being more than plain dmd or ldc2

Dub is very thorough about what it encodes in a build id even
collecting the compiler path. Therefore, if dub is not provided the
exact same compiler path that meson got during setup, the dependency
would not be found and the test would fail.

Signed-off-by: Andrei Horodniceanu <a.horodniceanu@proton.me>

Author: the-horo

test cases/d/14 dub with deps/meson.build

@@ -12,12 +12,9 @@ endif
 
 if meson.get_compiler('d').get_id() == 'gcc'
     error('MESON_SKIP_TEST: can\'t build dependencies with GDC')
-elif meson.get_compiler('d').get_id() == 'llvm'
-    dc = 'ldc2'
-elif meson.get_compiler('d').get_id() == 'dmd'
-    dc = 'dmd'
 endif
 
+dc = meson.get_compiler('d').cmd_array()[0]
 arch = host_machine.cpu_family()
 
 if host_machine.system() == 'windows'