support/scripts/gen-bootlin-toolchains: adjust dependencies of i686 toolchains

The Bootlin i686 toolchain was already made available only on BR2_i386
with !BR2_x86_i486 && !BR2_x86_i586 && !BR2_x86_1000. However, this
was not sufficient as a few other architecture variants of BR2_i386
are "lower" than i686, and they need to be excluded as well.

Allows to fix:

  http://autobuild.buildroot.net/results/56ac1a8fa5b34a9ca10eef98ae9fb090b8c762c4/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit 26dee54e428679920336f0fcbece826f8cbf23ec)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/scripts/gen-bootlin-toolchains

@@ -253,7 +253,12 @@ arches = {
         'conditions': ['BR2_i386',
                        '!BR2_x86_i486',
                        '!BR2_x86_i586',
-                       '!BR2_x86_x1000'],
+                       '!BR2_x86_x1000',
+                       '!BR2_x86_pentium_mmx',
+                       '!BR2_x86_geode',
+                       '!BR2_x86_c3',
+                       '!BR2_x86_winchip_c6',
+                       '!BR2_x86_winchip2'],
         'test_options': ['BR2_i386',
                          'BR2_x86_i686'],
         'prefix': 'i686',