[VOL-1866] Changed module dependency to v12.0.0 of k8s client-go and v1.15.4 of k8s api/apimachinery in sync with other voltha components

Had to use pseudo-version corresponding to v12.0.0 of k8s client-go
because golang proxy is no longer serving the modules not complying
to Semantic Import Versioning rules including client-go v12.0.0.
Refer to https://github.com/kubernetes/client-go/issues/631 and
https://github.com/golang/go/issues/33558

Change-Id: I2e558bab7f0702f230761319eb5392a7d0532ea3
diff --git a/vendor/golang.org/x/text/unicode/norm/composition.go b/vendor/golang.org/x/text/unicode/norm/composition.go
index bab4c5d..e2087bc 100644
--- a/vendor/golang.org/x/text/unicode/norm/composition.go
+++ b/vendor/golang.org/x/text/unicode/norm/composition.go
@@ -407,7 +407,7 @@
 
 // decomposeHangul algorithmically decomposes a Hangul rune into
 // its Jamo components.
-// See http://unicode.org/reports/tr15/#Hangul for details on decomposing Hangul.
+// See https://unicode.org/reports/tr15/#Hangul for details on decomposing Hangul.
 func (rb *reorderBuffer) decomposeHangul(r rune) {
 	r -= hangulBase
 	x := r % jamoTCount
@@ -420,7 +420,7 @@
 }
 
 // combineHangul algorithmically combines Jamo character components into Hangul.
-// See http://unicode.org/reports/tr15/#Hangul for details on combining Hangul.
+// See https://unicode.org/reports/tr15/#Hangul for details on combining Hangul.
 func (rb *reorderBuffer) combineHangul(s, i, k int) {
 	b := rb.rune[:]
 	bn := rb.nrune
@@ -461,6 +461,10 @@
 // It should only be used to recompose a single segment, as it will not
 // handle alternations between Hangul and non-Hangul characters correctly.
 func (rb *reorderBuffer) compose() {
+	// Lazily load the map used by the combine func below, but do
+	// it outside of the loop.
+	recompMapOnce.Do(buildRecompMap)
+
 	// UAX #15, section X5 , including Corrigendum #5
 	// "In any character sequence beginning with starter S, a character C is
 	//  blocked from S if and only if there is some character B between S