1504 - CSAssembly requires a C# Compiler.
Description
    
CSAssembly requires a C# compiler to function correctly. Other compiler types should not be used.
    
Example
    
Config:
    Compiler( 'Compiler' )
{
    .Executable         = 'cl.exe' // Not a C# compiler
}
CSAssembly( 'CSharp' )
{
    .Compiler           = 'Compiler'
    .CompilerOptions    = '/out:"%2" /target:library "%1"'
    .CompilerInputFiles = 'src/file.cs'
    .CompilerOutput     = 'out/output.dll'
}
Output:
C:\test\fbuild.bff(6,1): FASTBuild Error #1504 - CSAssembly() - CSAssembly requires a C# Compiler.
CSAssembly( 'CSharp' )
^
\--here
Fix:
Compiler( 'Compiler' )
{
    .Executable         = 'csc.exe'
}
CSAssembly( 'CSharp' )
{
    .Compiler           = 'Compiler'
    .CompilerOptions    = '/out:"%2" /target:library "%1"'
    .CompilerInputFiles = 'src/file.cs'
    .CompilerOutput     = 'out/output.dll'
}
    