[amtk] build: small simplification

[Sébastien Wilmet <swilmet src gnome org>]

commit f1c5c0cf4786d6c2e725d8473a9ca209cc22417d
Author: Sébastien Wilmet <sebastien wilmet gmail com>
Date:   Thu Sep 9 18:26:03 2021 +0200

    build: small simplification
    
    The variable is no longer needed after the previous commits.

 amtk/meson.build | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
---
diff --git a/amtk/meson.build b/amtk/meson.build
index 0e8a118..e663d77 100644
--- a/amtk/meson.build
+++ b/amtk/meson.build
@@ -44,7 +44,6 @@ amtk_enum_types = GNOME.mkenums_simple(
   install_dir: headers_install_dir
 )
 
-amtk_static_lib_c_args = [ '-DAMTK_COMPILATION' ]
 amtk_static_lib = static_library(
   'amtk-static',
   [amtk_public_c_files,
@@ -52,7 +51,7 @@ amtk_static_lib = static_library(
   pic: true, # amtk_static_lib is linked in a shared library.
   include_directories: ROOT_INCLUDE_DIR,
   dependencies: AMTK_DEPS,
-  c_args: amtk_static_lib_c_args
+  c_args: '-DAMTK_COMPILATION'
 )
 
 # For unit tests, to be able to test private functions.