Revert "Revert "Suppress Ada.Environment_Variables.Set known memory leak report""

This reverts commit e07494e.

Author: AnthonyLeonardoGracio

testsuite/leaks.supp

@@ -83,3 +83,12 @@
    fun:libadalang__implementation__c___elabb
    fun:adalanginit
 }
+
+{
+   Suppress Ada.Environment_Variables.Set known memory leak report
+   Memcheck:Leak
+   match-leak-kinds: definite
+   fun:malloc
+   fun:__gnat_setenv
+   fun:ada__environment_variables__set
+}