project: Minor meson improvements.

This patch makes some minor improvements to the meson build system.
The changes are as follows:

* Avoid conditional statements when setting config.h values.
* Ordered calendar dependencies.
* Reused variables derived from options.
* Removed unnecessary new line in the output at the configuration's
  end.
* Use set10 function avoiding the trinary operator.
* Removed dependencies on the libgcal dependency, as they are not
  needed.

https://bugzilla.gnome.org/show_bug.cgi?id=786481

src/meson.build

@@ -75,7 +75,7 @@ sources += gnome.gdbus_codegen(
 
 debug_conf = configuration_data()
 debug_conf.set('BUGREPORT_URL', package_bugreport)
-debug_conf.set('ENABLE_TRACING', (enable_tracing ? 1 : 0))
+debug_conf.set10('ENABLE_TRACING', enable_tracing)
 
 debug = 'gcal-debug.h'
 
@@ -108,6 +108,5 @@ libgcal = shared_library(
 
 libgcal_dep = declare_dependency(
   link_with: libgcal,
-  include_directories: src_inc,
-  dependencies: calendar_deps
+  include_directories: src_inc
 )