Remove jumbo usage in pdf/BUILD.gn

That is the only GN file in the pdf/ subdirectory.

Bug: 1020676
Change-Id: I2495ab9b5976957270298b8aed703f4d4c858844
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1895865Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711843}

pdf/BUILD.gn

@@ -4,7 +4,6 @@
 
 import("//build/buildflag_header.gni")
 import("//build/config/features.gni")
-import("//build/config/jumbo.gni")
 import("//pdf/features.gni")
 import("//testing/test.gni")
 import("//third_party/pdfium/pdfium.gni")
@@ -27,7 +26,7 @@ if (enable_pdf) {
     }
   }
 
-  jumbo_static_library("pdf") {
+  static_library("pdf") {
     configs += [ ":pdf_common_config" ]
     deps = [
       ":features",