Mass rewrite dtors to use "= default".

A simple search and replace with sed s/::~\(.*\) {}$/::~\1 = default;/
works surprisingly well.

Change-Id: Ie958265266e504006061e8f1b957046dfecd70dc
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/70251
Reviewed-by: Daniel Hosseinian <dhoss@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_annotiteration.cpp b/fpdfsdk/cpdfsdk_annotiteration.cpp
index d256950..fa9a5ea 100644
--- a/fpdfsdk/cpdfsdk_annotiteration.cpp
+++ b/fpdfsdk/cpdfsdk_annotiteration.cpp
@@ -37,4 +37,4 @@
     m_List.emplace_back(pAnnot);
 }
 
-CPDFSDK_AnnotIteration::~CPDFSDK_AnnotIteration() {}
+CPDFSDK_AnnotIteration::~CPDFSDK_AnnotIteration() = default;