linker: LoadSegments: Factor out ZeroFillSegment()

This is a preparatory patch for 16KiB app compat. No functional change
is introduced.

Bug: 339709616
Test: atest -c linker-unit-tests
Change-Id: If24c85b565c305e36bae97525087328aea7813b4
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
diff --git a/linker/linker_phdr.h b/linker/linker_phdr.h
index c7320ae..4028062 100644
--- a/linker/linker_phdr.h
+++ b/linker/linker_phdr.h
@@ -69,6 +69,7 @@
   [[nodiscard]] bool ReadPadSegmentNote();
   [[nodiscard]] bool ReserveAddressSpace(address_space_params* address_space);
   [[nodiscard]] bool MapSegment(size_t seg_idx, size_t len);
+  void ZeroFillSegment(const ElfW(Phdr)* phdr);
   [[nodiscard]] bool LoadSegments();
   [[nodiscard]] bool FindPhdr();
   [[nodiscard]] bool FindGnuPropertySection();