Add -B/--backtrace option to RGBASM and RGBLINK (#1787)

contrib/bash_compl/_rgbasm.bash

@@ -28,6 +28,7 @@ _rgbasm_completions() {
 		[V]="version:normal"
 		[W]="warning:warning"
 		[w]=":normal"
+		[B]="backtrace:unk"
 		[b]="binary-digits:unk"
 		[D]="define:unk"
 		[E]="export-all:normal"

contrib/bash_compl/_rgblink.bash

@@ -12,6 +12,7 @@ _rgblink_completions() {
 		[W]="warning:warning"
 		[M]="no-sym-in-map:normal"
 		[d]="dmg:normal"
+		[B]="backtrace:unk"
 		[l]="linkerscript:glob-*"
 		[m]="map:glob-*.map"
 		[n]="sym:glob-*.sym"