feat(bombadil): add 3rd party fallback completion loader

https://github.com/oknozor/toml-bombadil#shell-completions

Author: scop

completions/Makefile.am

@@ -32,6 +32,7 @@ cross_platform = 2to3 \
 		badblocks \
 		bind \
 		bk \
+		_bombadil \
 		brctl \
 		btdownloadheadless.py \
 		bts \

completions/_bombadil

@@ -0,0 +1,8 @@
+# 3rd party completion loader for commands emitting        -*- shell-script -*-
+# their completion using "$cmd generate-completions bash".
+#
+# This serves as a fallback in case the completion is not installed otherwise.
+
+eval -- "$("$1" generate-completions bash 2>/dev/null)"
+
+# ex: filetype=sh

test/fallback/completions/Makefile.am

@@ -1,6 +1,7 @@
 EXTRA_DIST = \
 	argc \
 	adb \
+	bombadil \
 	cal \
 	cargo \
 	chfn \

test/fallback/completions/bombadil

@@ -0,0 +1 @@
+../../../completions/_bombadil