Revert "C++: Implement compilation_build_mode"

Author: calumgrant

cpp/downgrades/f0156f5f88ab5967c79162012c20f30600ca5ebf/old.dbscheme

@@ -112,7 +112,4 @@ class Compilation extends @compilation {
    * termination, but crashing due to something like a segfault is not.
    */
   predicate normalTermination() { compilation_finished(this, _, _) }
-
-  /** Holds if this compilation was compiled using the "none" build mode. */
-  predicate buildModeNone() { compilation_build_mode(this, 0) }
 }

cpp/downgrades/f0156f5f88ab5967c79162012c20f30600ca5ebf/semmlecode.cpp.dbscheme

@@ -46,22 +46,6 @@ compilation_args(
     string arg : string ref
 );
 
-/**
- * Optionally, record the build mode for each compilation.
- */
-compilation_build_mode(
-    unique int id : @compilation ref,
-    int mode : int ref
-);
-
-/*
-case @compilation_build_mode.mode of
-  0 = @build_mode_none
-| 1 = @build_mode_manual
-| 2 = @build_mode_auto
-;
-*/
-
 /**
  * The source files that are compiled by a compiler invocation.
  * If `id` is for the compiler invocation