Fix build with pdf_is_complete_lib=true and pdf_is_standalone=true

In standalone builds, //:pdfium is jumbo_component, which forwards to a
regular component.  When is_component_build == true, the behavior of
component is to forward to a source_set when sources is not defined, and
forward to a static_library otherwise.  Since //:pdfium has no sources
(but instead pulls in many dependencies as sources), it will be a
source_set, which is not what we want for standalone builds.  Instead,
force it to be a static_library.

BUG=pdfium:1393
R=thestig

Change-Id: I3c4c090d4bcbfc52406a70bb9abaee00b0172198
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/60770
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Auto-Submit: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/BUILD.gn b/BUILD.gn
index 3ce1e08..c7c1638 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -192,6 +192,7 @@
   }
 
   if (pdf_is_complete_lib) {
+    target_type = "static_library"
     complete_static_lib = true
     configs -= [ "//build/config/compiler:thin_archive" ]
   }