Init PDFium in fuzzer code

Due to the partition alloc change we need to initialize the PDFium
library in the fuzzers now. This will initialize the needed partitions.
Without this, we fail in various places when attempting to create items
into the partitions

Bug: pdfium:687
Change-Id: I1c40ae3f442cb781cfdb7545b022ee1f4e64e264
Reviewed-on: https://pdfium-review.googlesource.com/3246
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
diff --git a/testing/libfuzzer/BUILD.gn b/testing/libfuzzer/BUILD.gn
index 9ba8e32..d9dc0ee 100644
--- a/testing/libfuzzer/BUILD.gn
+++ b/testing/libfuzzer/BUILD.gn
@@ -25,7 +25,7 @@
 
 template("pdfium_fuzzer") {
   source_set(target_name) {
-    sources = invoker.sources
+    sources = invoker.sources + [ "pdf_fuzzer_init.cc" ]
     deps = [
       "../..:pdfium",
     ]