DPRINTF(): Fix format, handle non-gcc, simplify.
DPRINTF(): Fix format, handle non-gcc, simplify.

Add C99-required 1st parameter.  Disable for for non-gcc.  Simplify.
GNU extension #define DPRINTF(<no 1st arg>...) -> GNU ext ,##__VA_ARGS__.
Fix __LINE__ format %ld -> %d.

bobek-balinek/BlueJet