build: Allow valadoc to find libhandy vapi when built from a subproject

meson.build

@@ -118,6 +118,7 @@ if libunwind_dep.found()
 endif
 
 # Handy 1.0 is still rather new
+libhandy_vapi = ''
 if not libhandy.found()
   libhandy_project = subproject(
     'libhandy',
@@ -130,9 +131,10 @@ if not libhandy.found()
   libhandy = declare_dependency(
     dependencies: [
       libhandy_project.get_variable('libhandy_dep'),
-      libhandy_project.get_variable('libhandy_vapi'),
+      libhandy_project.get_variable('libhandy_vapi')
     ]
   )
+  libhandy_vapi = meson.build_root() / 'subprojects' / 'libhandy' / 'src'
 endif
 
 # Optional dependencies

src/meson.build

@@ -138,7 +138,11 @@ valadoc_dependencies = [
 valadoc_dep_args = []
 foreach dep : valadoc_dependencies
   valadoc_dep_args += '--pkg'
-  valadoc_dep_args += dep.name()
+  if dep != libhandy
+    valadoc_dep_args += dep.name()
+  else
+    valadoc_dep_args += 'libhandy-1'
+  endif
 endforeach
 valadoc_dep_args += [ '--pkg', 'posix' ]
 
@@ -146,6 +150,9 @@ valadoc_vapi_dirs = [
   vapi_dir,
   meson.current_build_dir()
 ]
+if libhandy_vapi != ''
+  valadoc_vapi_dirs += libhandy_vapi
+endif
 
 valadoc_vapidir_args = []
 foreach dir : valadoc_vapi_dirs