Added evmod_glfw as subproject

Since the dependency doesn't require linkage to the generated library,
there is no reason for meson to generate build commands for the library
without it being explicitly specified as a subproject.

Signed-off-by: Robear Selwans <robear.selwans@outlook.com>

meson.build

@@ -4,7 +4,7 @@ project('evol-sandbox', 'c',
 
 evol_dep = dependency('evol')
 
-# subproject('evmod_glfw')
+subproject('evmod_glfw')
 evmodglfw_dep = dependency('evmod_glfw')
 
 sandbox_incdir = []