[gnome-calculator] GCalc: fix build using -Ddisable-ui=true

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit bfd6c9f92c10cce79273cbdab180095a84372c7a
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Apr 13 23:16:27 2022 -0500

    GCalc: fix build using -Ddisable-ui=true

 doc/meson.build     | 1 +
 gcalc/meson.build   | 1 +
 libmpfr/meson.build | 2 ++
 3 files changed, 4 insertions(+)
---
diff --git a/doc/meson.build b/doc/meson.build
index 752e6896..0ca92e71 100644
--- a/doc/meson.build
+++ b/doc/meson.build
@@ -14,6 +14,7 @@ if get_option('gcalc')
                                '--package-version='+meson.project_version(),
                                '--vapidir='+gcalc_sources_dir,
                                '--vapidir='+gcalc_build_dir,
+                               '--vapidir='+libmpfr_vapi_dir,
                                '--pkg=glib-2.0',
                                '--pkg=gio-2.0',
                                '--pkg=gee-0.8',
diff --git a/gcalc/meson.build b/gcalc/meson.build
index 30e1461d..a0ea2692 100644
--- a/gcalc/meson.build
+++ b/gcalc/meson.build
@@ -116,6 +116,7 @@ gcalc_exported_deps = [
        gee,
        inc_rooth_dep,
        gcalc_inc_libh_dep,
+       libmpfr_inc_libh_dep,
 ]
 
 gcalc_deps = [
diff --git a/libmpfr/meson.build b/libmpfr/meson.build
index 5479de01..e8bdf0e1 100644
--- a/libmpfr/meson.build
+++ b/libmpfr/meson.build
@@ -6,6 +6,8 @@ lib_mpfrg_sources = files([
 libmpfr_inc_libh = include_directories ('.')
 libmpfr_inc_libh_dep = declare_dependency (include_directories : libmpfr_inc_libh)
 
+libmpfr_vapi_dir = meson.current_build_dir()
+
 lib_mpfrg = static_library ('mpfrg',
        lib_mpfrg_sources,
        vala_header: 'mpfrg.h',