patch 8.0.0954: /proc/self/exe might be a relative path

Problem:    /proc/self/exe might be a relative path.
Solution:   Make the path a full path. (James McCoy, closes #1983)

src/main.c

@@ -3597,36 +3597,35 @@ set_progpath(char_u *argv0)
 {
     char_u *val = argv0;
 
-# ifdef PROC_EXE_LINK
-    char    buf[MAXPATHL + 1];
-    ssize_t len;
-
-    len = readlink(PROC_EXE_LINK, buf, MAXPATHL);
-    if (len > 0)
-    {
-	buf[len] = NUL;
-	val = (char_u *)buf;
-    }
-# else
+# if defined(WIN32)
     /* A relative path containing a "/" will become invalid when using ":cd",
      * turn it into a full path.
      * On MS-Windows "vim" should be expanded to "vim.exe", thus always do
      * this. */
-#  ifdef WIN32
     char_u *path = NULL;
 
     if (mch_can_exe(argv0, &path, FALSE) && path != NULL)
 	val = path;
-#  else
-    char_u buf[MAXPATHL];
+# else
+    char_u	buf[MAXPATHL + 1];
+#  ifdef PROC_EXE_LINK
+    char	linkbuf[MAXPATHL + 1];
+    ssize_t	len;
 
-    if (!mch_isFullName(argv0))
+    len = readlink(PROC_EXE_LINK, linkbuf, MAXPATHL);
+    if (len > 0)
     {
-	if (gettail(argv0) != argv0
-			   && vim_FullName(argv0, buf, MAXPATHL, TRUE) != FAIL)
-	    val = buf;
+	linkbuf[len] = NUL;
+	val = (char_u *)linkbuf;
     }
 #  endif
+
+    if (!mch_isFullName(val))
+    {
+	if (gettail(val) != val
+			   && vim_FullName(val, buf, MAXPATHL, TRUE) != FAIL)
+	    val = buf;
+    }
 # endif
 
     set_vim_var_string(VV_PROGPATH, val, -1);

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    954,
 /**/
     953,
 /**/