Cmake: improve ncurses detection (#25776)

* Optionally enable ccmake in cmake

Renames ncurses variant to `ccmake` since that's how users know it, and
explicitly enable/disable `BUILD_CursesDialog`.

* Make cmake locate its dependencies with CMAKE_PREFIX_PATH, and set rpath flags too

* Undo variant name & defaults change

var/spack/repos/builtin/packages/cmake/package.py

@@ -5,6 +5,8 @@
 
 import re
 
+import spack.build_environment
+
 
 class Cmake(Package):
     """A cross-platform, open-source build system. CMake is a family of
@@ -277,6 +279,17 @@ def bootstrap_args(self):
         if '+ownlibs' in spec:
             args.append('-DCMAKE_USE_OPENSSL=%s' % str('+openssl' in spec))
 
+        args.append('-DBUILD_CursesDialog=%s' % str('+ncurses' in spec))
+
+        # Make CMake find its own dependencies.
+        rpaths = spack.build_environment.get_rpaths(self)
+        prefixes = spack.build_environment.get_cmake_prefix_path(self)
+        args.extend([
+            '-DCMAKE_INSTALL_RPATH_USE_LINK_PATH=OFF',
+            '-DCMAKE_INSTALL_RPATH={0}'.format(";".join(str(v) for v in rpaths)),
+            '-DCMAKE_PREFIX_PATH={0}'.format(";".join(str(v) for v in prefixes))
+        ])
+
         return args
 
     def bootstrap(self, spec, prefix):