[PATCH 2/3] doc: Document testsuite check_effective_target_tail_call

[Hans-Peter Nilsson <hp@axis.com>]

Will commit as obvious, when the 1/3 tail_call is applied.
-- >8 --
Spot-checked the PDF output for sanity.

	* doc/sourcebuild.texi: Document check_effective_target_tail_call.
---
 gcc/doc/sourcebuild.texi | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index c348a1e47cc3..80bef7f0a0e2 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -2844,6 +2844,9 @@ Target supports named sections.
 Target uses natural alignment (aligned to type size) for types of
 32 bits or less.
 
+@item tail_call
+Target supports tail-call optimizations.
+
 @item target_natural_alignment_64
 Target uses natural alignment (aligned to type size) for types of
 64 bits or less.
-- 
2.30.2