pdfium: remove non-public headers from include path

This was only needed to use upstream scopers, but we don't use those
anymore.

Change-Id: Idac60119d4d4e8587170fe3e5c69b3ec069e6a6b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/104069
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
diff --git a/RepositoryExternal.mk b/RepositoryExternal.mk
index 19421d4..f0cad01 100644
--- a/RepositoryExternal.mk
+++ b/RepositoryExternal.mk
@@ -4163,7 +4163,6 @@ endef
ifneq ($(ENABLE_PDFIUM),)
define gb_LinkTarget__use_pdfium
$(call gb_LinkTarget_set_include,$(1),\
       -I$(call gb_UnpackedTarball_get_dir,pdfium) \
       -I$(call gb_UnpackedTarball_get_dir,pdfium)/public \
       -DCOMPONENT_BUILD \
       $$(INCLUDE) \