Stabilize keyval module

We have experimented with the module for about a year in a qemu
branch (https://wiki.qemu.org/Features/Meson), and we would like to
start moving the build system to meson. For that, keyval should have
the stability guarantees.

Cc: Paolo Bonzini <pbonzini@redhat.com>

docs/markdown/Keyval-module.md

@@ -1,5 +1,5 @@
 ---
-short-description: Unstable keyval module
+short-description: Keyval module
 authors:
     - name: Mark Schulte, Paolo Bonzini
       years: [2017, 2019]
@@ -23,7 +23,7 @@ chosen the configuration options), output a ".config" file.
 The module may be imported as follows:
 
 ``` meson
-keyval = import('unstable-keyval')
+keyval = import('keyval')
 ```
 
 The following functions will then be available as methods on the object

docs/markdown/snippets/keyval.md

@@ -0,0 +1,7 @@
+## `unstable-keyval` is now stable `keyval`
+
+The `unstable-keyval` has been renamed to `keyval` and now promises stability
+guarantees.
+
+Meson will print a warning when you load an `unstable-` module that has been
+stabilised (so `unstable-keyval` is still accepted for example).

test cases/common/222 source set realistic example/meson.build

@@ -9,7 +9,7 @@ if cppid == 'pgi'
 endif
 
 ss = import('sourceset')
-keyval = import('unstable-keyval')
+keyval = import('keyval')
 
 zlib = declare_dependency(compile_args: '-DZLIB=1')
 another = declare_dependency(compile_args: '-DANOTHER=1')

test cases/keyval/1 basic/meson.build

@@ -1,6 +1,6 @@
 project('keyval basic test')
 
-k = import('unstable-keyval')
+k = import('keyval')
 conf = k.load('.config')
 
 if not conf.has_key('CONFIG_VAL1')

test cases/keyval/2 subdir/dir/meson.build

@@ -1,5 +1,5 @@
 
-k = import('unstable-keyval')
+k = import('keyval')
 
 conf = k.load(meson.source_root() / '.config')
 

test cases/keyval/3 load_config files/dir/meson.build

@@ -1,5 +1,5 @@
 
-k = import('unstable-keyval')
+k = import('keyval')
 
 conf = k.load(files('config'))
 

test cases/keyval/4 load_config builddir/meson.build

@@ -1,6 +1,6 @@
 project('keyval builddir test')
 
-k = import('unstable-keyval')
+k = import('keyval')
 
 out_conf = configure_file(input: 'config', output: 'out-config', copy: true)
 conf = k.load(out_conf)