Show +YJIT in version string and RUBY_DESCRIPTION

There might be code out there that expect `ruby -v` to print only one
line. Since MJIT shows +JIT in `ruby -v` and RUBY_DESCRIPTION, let's
show +YJIT.

The crash report doesn't show anything about MJIT, so adjust the test.
The "test_ruby_version" test was unaware of RUBY_YJIT_ENABLE and so
was failing when the variable is set and inherited into the children
processes it spawns. Explicitly unset the variable in the test.

1 files changed, 7 insertions, 3 deletions

diff --git a/version.c b/version.c
index e8bf51d2dc..5bfc663b4e 100644
--- a/version.c
+++ b/version.c
@@ -43,6 +43,7 @@ const char ruby_platform[] = RUBY_PLATFORM;
 const int ruby_patchlevel = RUBY_PATCHLEVEL;
 const char ruby_description[] = RUBY_DESCRIPTION_WITH("");
 static const char ruby_description_with_jit[] = RUBY_DESCRIPTION_WITH(" +JIT");
+static const char ruby_description_with_yjit[] = RUBY_DESCRIPTION_WITH(" +YJIT");
 const char ruby_copyright[] = RUBY_COPYRIGHT;
 const char ruby_engine[] = "ruby";
 
@@ -105,6 +106,9 @@ Init_ruby_description(void)
     if (MJIT_OPTS_ON) {
         description = MKSTR(description_with_jit);
     }
+    else if (rb_yjit_enabled_p()) {
+        description = MKSTR(description_with_yjit);
+    }
     else {
         description = MKSTR(description);
     }
@@ -121,13 +125,13 @@ ruby_show_version(void)
     if (MJIT_OPTS_ON) {
         PRINT(description_with_jit);
     }
+    else if (rb_yjit_enabled_p()) {
+        PRINT(description_with_yjit);
+    }
     else {
         PRINT(description);
     }
 
-    if (rb_yjit_enabled_p()) {
-        fputs("YJIT is enabled\n", stdout);
-    }
 #ifdef RUBY_LAST_COMMIT_TITLE
     fputs("last_commit=" RUBY_LAST_COMMIT_TITLE, stdout);
 #endif