build-sys: enable colored diagnostics if available
diff --git a/configure.ac b/configure.ac
index e7416f6..38187a1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -179,6 +179,7 @@
 		       -Wuninitialized \
 		       -fno-common \
 		       -fdiagnostics-show-option \
+		       -fdiagnostics-color=auto \
 		       -fvisibility=hidden \
 		       -ffunction-sections \
 		       -fdata-sections])