patch 8.0.1607: --clean loads user settings from .gvimrc

Problem:    --clean loads user settings from .gvimrc.
Solution:   Behave like "-U NONE" was used. (Ken Takata)

Author: brammool

runtime/doc/starting.txt

@@ -510,11 +510,12 @@ a slash.  Thus "-R" means recovery and "-/R" readonly.
 		{not in Vi}
 
 							*--clean*
---clean		Equal to "-u DEFAULTS -i NONE":
+--clean		Equal to "-u DEFAULTS -U NONE -i NONE":
 		- initializations from files and environment variables is
 		  skipped
 		- the |defaults.vim| script is loaded, which implies
 		  'nocompatible': use Vim defaults
+		- no |gvimrc| script is loaded
 		- no viminfo file is read or written
 		- the home directory is excluded from 'runtimepath'
 							*-x*

src/main.c

@@ -1881,6 +1881,9 @@ command_line_scan(mparm_T *parmp)
 		else if (STRNICMP(argv[0] + argv_idx, "clean", 5) == 0)
 		{
 		    parmp->use_vimrc = (char_u *)"DEFAULTS";
+#ifdef FEAT_GUI
+		    use_gvimrc = (char_u *)"NONE";
+#endif
 		    parmp->clean = TRUE;
 		    set_option_value((char_u *)"vif", 0L, (char_u *)"NONE", 0);
 		}

src/version.c

@@ -766,6 +766,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1607,
 /**/
     1606,
 /**/