Remove CFX_PrivateData from CPDF_ModuleMgr

Its only used to store one object, so replace it with a unique_ptr
to a class with a virtual dtor.  Rename the prototypical class with
virtual dtor from CFX_DestructObject to CFX_Deletable. Rename the
fx_basic_module.cpp to cfx_modulemgr.cpp to match the one class
in it.

Review-Url: https://codereview.chromium.org/2013483003
diff --git a/BUILD.gn b/BUILD.gn
index ee5aad5..c6c279e 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -244,7 +244,7 @@
 
 static_library("fpdfapi") {
   sources = [
-    "core/fpdfapi/fpdf_basic_module.cpp",
+    "core/fpdfapi/cpdf_modulemgr.cpp",
     "core/fpdfapi/fpdf_cmaps/CNS1/Adobe-CNS1-UCS2_5.cpp",
     "core/fpdfapi/fpdf_cmaps/CNS1/B5pc-H_0.cpp",
     "core/fpdfapi/fpdf_cmaps/CNS1/B5pc-V_0.cpp",