Version details: 1.4.2

The D language has its own syntax for declaring functions with external linkage
and for specifying struct member alignment.

This syntax looks like this:

    extern(C) void qwert();

    align(2) yuiop;

Doxygen doesn't currently understand this aspect of D, and so such declarations
do not parse correctly.

Similar in syntax is the pragma, which can also take comma-separated arguments.
 The same code could be used to handle all three keywords.


Steps to reproduce:
1. Create a D file containing these lines:

    extern(C) void qwert();

    align(2) struct Yuiop {
        char asdfg;
        int hjkl;
    }

    pragma(Zxcvb, 42) int nm;

2. Run Doxygen.


Actual results:

extern(C), align(2) and pragma(Zxcvb, 42) are misparsed as function signatures,
leading to this output (underscores denote links):

    Functions
    _extern_ (C) void qwert()
    _align_ (2) struct Yuiop
    _pragma_ (Zxcvb, 42) int nm
    ----

    Function Documentation

    align( 2 )

    extern( C )

    pragma( Zxcvb ,
            42
          )


Expected results:

Parse the whole token sequence extern(...), align(...) or pragma(...) as a
declaration attribute.

Note that align and extern are also valid attributes without the (...) portion.