environment: do not raise exception in detect_cuda_compiler

when the compiler is not a string.  When the compiler
is set in the build configuration (required, for example,
in a cross-build setup), the compiler setting is already
a list, which is the desired type.

Signed-off-by: Matt Madison <matt@madison.systems>

mesonbuild/environment.py

@@ -1208,8 +1208,6 @@ class Environment:
         for compiler in compilers:
             if isinstance(compiler, str):
                 compiler = [compiler]
-            else:
-                raise EnvironmentException()
             arg = '--version'
             try:
                 p, out, err = Popen_safe(compiler + [arg])