GHC driver behaviour switch

[kyra]

With GHC 6.4.x I was able to use a ghc driver to compile .cpp sources. 
Now, with GHC HEAD I cannot. GHC HEAD now ALWAYS enforces "treat as .c" 
option.

Let's compare "DriverPipeline.hs".

GHC 6.4.x:

let langopt | hcc = [ SysTools.Option "-x", SysTools.Option "c"]
            | otherwise = [ ]
 
SysTools.runCc dflags (
    -- force the C compiler to interpret this file as C when
    -- compiling .hc files, by adding the -x c option.
    -- Also useful for plain .c files, just in case GHC saw a
    -- -x c option.
        langopt ++ ...


GHC HEAD:

SysTools.runCc dflags (
    -- force the C compiler to interpret this file as C when
    -- compiling .hc files, by adding the -x c option.
    -- Also useful for plain .c files, just in case GHC saw a
    -- -x c option.
        [ SysTools.Option "-x", SysTools.Option "c"] ++ ...


This completely breaks my build infrastructure. Could it be reversed?

Cheers,
Kyra