[vigiles/kconfig] Make sure there is a kernel config file before copying

In the event that we can't find a kernel config, even if VIGILES_KERNEL_CONFIG
is set (even to 'auto'), we don't want to tail if it ain't there.

This will happen if 'linux-dummy' is used for the 'virtual/kernel' target
(i.e. if the build is set up to use a kernel from an external tree) and
VIGILES_KERNEL_CONFIG is set to 'auto', since we'll attempt to check in
that build directory.

In order to correctly enable kernel config checking when using an external
kernel tree, VIGILES_KERNEL_CONFIG must be set to the path of the .config.

In addition to checking for the .config exists, this change also cleans the
symlink in the vigiles/ directory (if present) to prevent us from picking it
up and sending it during vigiles_check().

classes/vigiles.bbclass

@@ -265,9 +265,6 @@ python do_vigiles_kconfig() {
     import shutil
     from oe import recipeutils as oe
 
-    build_dir = os.path.relpath(d.getVar('B'))
-    kconfig_in = os.path.join(build_dir, '.config')
-
     vgls_pf = _get_kernel_pf(d)
     vgls_timestamp = d.getVar('VIGILES_TIMESTAMP')
 
@@ -277,20 +274,37 @@ python do_vigiles_kconfig() {
 
     bb.debug(1, "Translation: %s -> %s" % (kconfig_fname, kconfig_lname))
 
-    vigiles_kconfig = d.getVar('VIGILES_DIR_KCONFIG')
+    vigiles_kconfig_dir = d.getVar('VIGILES_DIR_KCONFIG')
     vigiles_dir = d.getVar('VIGILES_DIR')
-    kconfig_out = os.path.join(vigiles_kconfig, kconfig_fname)
+    kconfig_out = os.path.join(vigiles_kconfig_dir, kconfig_fname)
     kconfig_link = os.path.join(vigiles_dir, kconfig_lname)
 
-    if not os.path.exists(vigiles_kconfig):
-        bb.utils.mkdirhier(vigiles_kconfig)
+    if os.path.exists(kconfig_link):
+        os.remove(kconfig_link)
+
+    kconfig_in = d.getVar('VIGILES_KERNEL_CONFIG') or ''
 
-    bb.debug(1, "Copy: %s -> %s" % (os.path.relpath(kconfig_in), os.path.relpath(kconfig_out)))
+    if not kconfig_in:
+        return
+
+    if kconfig_in == 'auto':
+        build_dir = os.path.relpath(d.getVar('B'))
+        kconfig_in = os.path.join(build_dir, '.config')
+
+    if not os.path.exists(kconfig_in):
+        bb.warn("kernel config does not exist, skipping.")
+        bb.warn("kconfig path: %s" % kconfig_in)
+        return
+
+    if not os.path.exists(vigiles_kconfig_dir):
+        bb.utils.mkdirhier(vigiles_kconfig_dir)
+
+    bb.debug(1, "Copy: %s -> %s" %
+             (os.path.relpath(kconfig_in), os.path.relpath(kconfig_out)))
     shutil.copy(kconfig_in, kconfig_out)
 
-    if os.path.exists(kconfig_link):
-        os.remove(kconfig_link)
-    bb.debug(1, "Link: %s -> %s" % (os.path.relpath(kconfig_link), os.path.relpath(kconfig_out)))
+    bb.debug(1, "Link: %s -> %s" %
+             (os.path.relpath(kconfig_link), os.path.relpath(kconfig_out)))
     os.symlink(os.path.relpath(kconfig_out, vigiles_dir), kconfig_link)
 }
 
@@ -305,6 +319,7 @@ def vigiles_kconfig_depends(d)->str:
             kpref = d.getVar('PREFERRED_PROVIDER_virtual/kernel')
             if pn == kpref:
                 deps = ("%s:do_configure" % pn)
+
     return deps
 
 do_vigiles_kconfig[depends] += " ${@vigiles_kconfig_depends(d)} "
@@ -319,13 +334,8 @@ python do_vigiles_check() {
     vigiles_in = d.getVar('VIGILES_MANIFEST_LINK')
     vigiles_out = d.getVar('VIGILES_REPORT')
     vigiles_link = d.getVar('VIGILES_REPORT_LINK')
-
-
-    vigiles_kconfig = d.getVar("VIGILES_KERNEL_CONFIG") or ""
-    if vigiles_kconfig == "auto":
-        kconfig_lname = '.'.join([_get_kernel_pf(d), 'config'])
-        kconfig_path = os.path.join(d.getVar('VIGILES_DIR'), kconfig_lname)
-        vigiles_kconfig = kconfig_path if os.path.exists(kconfig_path) else ""
+    vigiles_kconfig = os.path.join(d.getVar('VIGILES_DIR'),
+                                   '.'.join([_get_kernel_pf(d), 'config']))
 
     bb.utils.export_proxies(d)
 
@@ -334,7 +344,7 @@ python do_vigiles_check() {
         bb.debug(1, "Using Manifest at: %s" % os.path.relpath(vigiles_in))
         bb.debug(1, "Writing Report to: %s" % os.path.relpath(vigiles_link))
 
-        if vigiles_kconfig:
+        if os.path.exists(vigiles_kconfig):
             bb.debug(1, "Using Kernel Config: %s" % os.path.relpath(vigiles_kconfig))
             args = args + ['-k', vigiles_kconfig]