tests: skip CVS tests for root

It is not uncommon for cvs to check for root and to refuse work
in that case.

Differential Revision: https://phab.mercurial-scm.org/D8395

tests/test-convert-cvs-branch.t

@@ -1,4 +1,4 b''
-#require cvs
+#require cvs no-root
 
 This is https://bz.mercurial-scm.org/1148
 and https://bz.mercurial-scm.org/1447

tests/test-convert-cvs-detectmerge.t

@@ -1,4 +1,4 b''
-#require cvs
+#require cvs no-root
 
 Test config convert.cvsps.mergefrom config setting.
 (Should test similar mergeto feature, but I don't understand it yet.)

tests/test-convert-cvs-synthetic.t

@@ -1,4 +1,4 b''
-#require cvs112
+#require cvs112 no-root
 
 This feature requires use of builtin cvsps!
 

tests/test-convert-cvs.t

@@ -1,4 +1,4 b''
-#require cvs
+#require cvs no-root
 
   $ cvscall()
   > {

tests/test-convert-cvsnt-mergepoints.t

@@ -1,4 +1,4 b''
-#require cvs
+#require cvs no-root
 
   $ filterpath()
   > {