patch 8.2.0573: using :version twice leaks memory

Problem:    using :version twice leaks memory
Solution:   Only initialize variables once. (Dominique Pelle, closes #5917)

src/globals.h

@@ -1258,7 +1258,7 @@ extern char *Version;
 #if defined(HAVE_DATE_TIME) && defined(VMS) && defined(VAXC)
 extern char longVersion[];
 #else
-EXTERN char *longVersion;
+EXTERN char *longVersion INIT(= NULL);
 #endif
 
 /*

src/testdir/Make_all.mak

@@ -285,6 +285,7 @@ NEW_TESTS = \
 	test_utf8 \
 	test_utf8_comparisons \
 	test_vartabs \
+	test_version \
 	$(TEST_VIM9) \
 	test_viminfo \
 	test_vimscript \

src/testdir/test_alot.vim

@@ -32,4 +32,5 @@ source test_tabline.vim
 source test_tagcase.vim
 source test_tagfunc.vim
 source test_unlet.vim
+source test_version.vim
 source test_wnext.vim

src/testdir/test_version.vim

@@ -0,0 +1,10 @@
+" Test :version Ex command
+
+func Test_version()
+  " version should always return the same string.
+  let v1 = execute('version')
+  let v2 = execute('version')
+  call assert_equal(v1, v2)
+
+  call assert_match("^\n\nVIM - Vi IMproved .*", v1)
+endfunc

src/version.c

@@ -54,6 +54,8 @@ init_longVersion(void)
     void
 init_longVersion(void)
 {
+    if (longVersion == NULL)
+    {
 	char *date_time = __DATE__ " " __TIME__;
 	char *msg = _("%s (%s, compiled %s)");
 	size_t len = strlen(msg)
@@ -67,6 +69,7 @@ init_longVersion(void)
 	else
 	    vim_snprintf(longVersion, len, msg,
 			  VIM_VERSION_LONG_ONLY, VIM_VERSION_DATE_ONLY, date_time);
+    }
 }
 # endif
 #else
@@ -738,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    573,
 /**/
     572,
 /**/