build: Avoid building files multiple times

We don't have to build each source for every test, instead we could
create a static library link it with every test, which will be a lot
faster.

plugins/dummy/meson.build

@@ -51,6 +51,7 @@ calls_dummy = shared_module(
   dummy_sources,
   dependencies: dummy_deps,
   include_directories: src_include,
+  link_with: libcalls,
   install: true,
   install_dir: dummy_install_dir
 )

plugins/mm/meson.build

@@ -51,6 +51,7 @@ calls_mm = shared_module(
   mm_sources,
   dependencies: mm_deps,
   include_directories: src_include,
+  link_with: libcalls,
   install: true,
   install_dir: mm_install_dir
 )

plugins/ofono/meson.build

@@ -54,7 +54,7 @@ calls_ofono = shared_module(
     src_include,
     include_directories('.')
   ],
-  link_with: gdbofono_lib,
+  link_with: [gdbofono_lib, libcalls],
   install: true,
   install_dir: ofono_install_dir
 )

plugins/sip/meson.build

@@ -69,6 +69,7 @@ calls_sip = shared_module(
   sip_sources,
   dependencies: sip_deps,
   include_directories: src_include,
+  link_with: libcalls,
   install: true,
   install_dir: sip_install_dir
 )