Encapsulate GLSL executable string, so it can be overridden (#4707)

Author: themkat

clients/lsp-glsl.el

@@ -40,7 +40,9 @@
 
 (lsp-register-client
  (make-lsp-client
-  :new-connection (lsp-stdio-connection lsp-glsl-executable)
+  :new-connection (lsp-stdio-connection
+                   (lambda ()
+                     lsp-glsl-executable))
   :activation-fn (lsp-activate-on "glsl")
   :priority -1
   :server-id 'glslls))