ci: add envtools support

This commit add envtools suppport to CI to verify if there
is no build issues.

Signed-off-by: Pierre-Jean Texier <pjtexier@koncepto.io>
Acked-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 84e79bf..a1c5b4f 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -145,6 +145,13 @@
   script:
     - make tools-only_config tools-only -j$(nproc)
 
+# Ensure env tools build
+Build envtools:
+  tags: [ 'all' ]
+  stage: testsuites
+  script:
+    - make tools-only_config envtools -j$(nproc)
+
 Run binman, buildman, dtoc and patman testsuites:
   tags: [ 'all' ]
   stage: testsuites