More accurate build and install with the bc preload option

Only when using preload, generate the header files and omit installation
of the Lua lang implementation files.

lang/meson.build

@@ -3,14 +3,19 @@ lang_sources = ['ast-boolean-const-eval.lua', 'ast-const-eval.lua', 'bcread.lua'
 luajit = find_program('luajit')
 
 lang_bc_headers = []
-foreach lua_source : lang_sources
-    lang_bc_headers += custom_target(lua_source + '.h',
-        input: lua_source,
-        output: '@[email protected]',
-        command: [luajit, '-b', '@INPUT@', '@OUTPUT@']
-    )
-endforeach
+
+if bytecode_preload
+    foreach lua_source : lang_sources
+        lang_bc_headers += custom_target(lua_source + '.h',
+            input: lua_source,
+            output: '@[email protected]',
+            command: [luajit, '-b', '@INPUT@', '@OUTPUT@']
+        )
+    endforeach
+endif
 
 lua_module_install_dir = 'share/lua/5.1'
 
-install_data(lang_sources, install_dir: lua_module_install_dir + '/lang')
+if not bytecode_preload
+    install_data(lang_sources, install_dir: lua_module_install_dir + '/lang')
+endif

meson.build

@@ -2,6 +2,8 @@ project('luajit-lang-toolkit', 'c', version : '1.0', default_options : 'c_std=c9
 
 pkg = import('pkgconfig')
 
+bytecode_preload = get_option('preload')
+
 lang_headers_dir = include_directories('.')
 
 subdir('lang')

src/meson.build

@@ -6,7 +6,7 @@ endif
 
 lang_sources = ['language.c', 'language_loaders.c']
 
-if get_option('preload')
+if bytecode_preload
     lang_sources += 'language_bcloader.c'
     lang_cflags += '-DBC_PRELOAD'
 endif