Fix compiledb SCons tool availability

SConstruct

@@ -956,25 +956,25 @@ if selected_platform in platform_list:
         env.vs_incs = []
         env.vs_srcs = []
 
-    if env["compiledb"]:
-        # Generating the compilation DB (`compile_commands.json`) requires SCons 4.0.0 or later.
-        from SCons import __version__ as scons_raw_version
-
-        scons_ver = env._get_major_minor_revision(scons_raw_version)
-
-        if scons_ver < (4, 0, 0):
-            print("The `compiledb=yes` option requires SCons 4.0 or later, but your version is %s." % scons_raw_version)
-            Exit(255)
+    # CompileDB
+    from SCons import __version__ as scons_raw_version
 
+    scons_ver = env._get_major_minor_revision(scons_raw_version)
+    if env["compiledb"] and scons_ver < (4, 0, 0):
+        # Generating the compilation DB (`compile_commands.json`) requires SCons 4.0.0 or later.
+        print("The `compiledb=yes` option requires SCons 4.0 or later, but your version is %s." % scons_raw_version)
+        Exit(255)
+    if scons_ver >= (4, 0, 0):
         env.Tool("compilation_db")
         env.Alias("compiledb", env.CompilationDatabase())
 
+    # Threads
     if env["threads"]:
         env.Append(CPPDEFINES=["THREADS_ENABLED"])
 
+    # Build subdirs, the build order is dependent on link order.
     Export("env")
 
-    # Build subdirs, the build order is dependent on link order.
     SConscript("core/SCsub")
     SConscript("servers/SCsub")
     SConscript("scene/SCsub")