gEDA: bug in pcb-1.7.2a Gerber output, and patch

[Larry Doolittle <ldoolitt-at-NOSPAMrecycle_dot_lbl_dot_gov>]

Anyone using pcb-1.7.2a for real Gerber output needs to apply this patch,
if they want boards to come out right [*].  Thanks to Stefan Petersen
and gerbv for helping me notice the error, before I wasted taxpayers
money with free software :-( .

gerbv-0.0.6 still can't render the output of pcb-1.7.2a, even with
this fix.  It needs to implement %LN and %LP first, so pcb can set
positive and negative modes to draw cutouts in polygons.

        - Larry Doolittle  <LRDoolittle@lbl.gov>

[*] And of course, even with the fix, I don't promise anything.

--- dev_rs274x.c.orig	Sun Dec 23 11:09:35 2001
+++ dev_rs274x.c	Sun Dec 23 11:10:35 2001
@@ -256,7 +256,7 @@
 		/* gather all aperture macros */
 	ALLLINE_LOOP(PCB->Data,
 		findApertureCode(&GBX_Apertures, line->Thickness, ROUND);
-		if (!TEST_FLAG(CLEARLINEFLAG, line))
+		if (TEST_FLAG(CLEARLINEFLAG, line))   /* XXX Sense of comparison fixed -- LRD */
 			findApertureCode(&GBX_Apertures, line->Thickness + line->Clearance, ROUND);
 	);
 	ELEMENT_LOOP(PCB->Data,