ATLAS: Create minimum 1x1 textures from ibar

Atlas extracted the ammo icons from ibar
Matrix-QW created a 1x1 ibar.png
Atlas then attempted to create a 0x0 ammo texture

Fixes #571

r_atlas.c

@@ -362,6 +362,12 @@ void CachePics_LoadAmmoPics(mpic_t* ibar)
 		realwidth = (newsh - newsl) * texWidth;
 		realheight = (newth - newtl) * texHeight;
 
+		// Cope with 1x1 transparent png files...(#571)
+		realwidth = max(realwidth, 1);
+		realheight = max(realheight, 1);
+		x_src = min(x_src, texWidth - 1);
+		y_src = min(y_src, texHeight - 1);
+
 		snprintf(name, sizeof(name), "hud_ammo_%d", i - WADPIC_SB_IBAR_AMMO1);
 
 		for (y = 0; y < realheight; ++y) {

release-notes-latest.md

@@ -10,6 +10,7 @@ Leaving these here as bugs between dev versions of 3.6 aren't in the release not
 - Fixed incomplete rendering when gibbed or dead in shallow water (reported by Matrix, #568)
 - Fixed tab key not switching tabs on serverinfo popup (reported by Hangtime, #555)
 - Fixed `/demo_jump_mark` not working if `/demo_jump_rewind` not set
+- Fixed coping with 1x1 ibar.png (reported by Matrix, #571)
 - Added `/gl_smoothmodels` back in (modern renderer only), (requested by Repast via [quakeworld.nu](https://www.quakeworld.nu/forum/topic/7508/why-is-the-command-glsmoothmodels-r))
 - Added `/demo_jump_skip_messages` to determine if messages should be printed to console during demo jump
 - Added `/demo_jump_end` to jump to next intermission point or end of demo (requested by Hangtime, #564)