disable the $PATH search for the PKG_CONFIG tool.  it isn't needed and just
gets in the way when setting to a value that might not yet exist.

--- ncurses-6.0/configure
+++ ncurses-6.0/configure
@@ -3533,7 +3533,7 @@
 esac
 
 test -z "$PKG_CONFIG" && PKG_CONFIG=none
-if test "$PKG_CONFIG" != none ; then
+if false ; then
 
 if test "x$prefix" != xNONE; then
 	cf_path_syntax="$prefix"