Remove PAGE_SIZE call sites.

To enable experiments with non-4KiB page sizes, introduce
an inline page_size() function that will either return the runtime
page size (if PAGE_SIZE is not 4096) or a constant 4096 (elsewhere).
This should ensure that there are no changes to the generated code on
unaffected platforms.

Test: source build/envsetup.sh
      lunch aosp_cf_arm64_16k_phone-userdebug
      m -j32 installclean
      m -j32
Test: launch_cvd \
  -kernel_path /path/to/out/android14-5.15/dist/Image \
  -initramfs_path /path/to/out/android14-5.15/dist/initramfs.img \
  -userdata_format=ext4
Bug: 277272383
Bug: 230790254
Change-Id: Ic0ed98b67f7c6b845804b90a4e16649f2fc94028
diff --git a/linker/linker_utils_test.cpp b/linker/linker_utils_test.cpp
index 44907da..0b881d4 100644
--- a/linker/linker_utils_test.cpp
+++ b/linker/linker_utils_test.cpp
@@ -33,6 +33,7 @@
 #include <gtest/gtest.h>
 
 #include "linker_utils.h"
+#include "platform/bionic/page.h"
 
 TEST(linker_utils, format_string) {
   std::vector<std::pair<std::string, std::string>> params = {{ "LIB", "lib32"}, { "SDKVER", "42"}};
@@ -104,9 +105,9 @@
 }
 
 TEST(linker_utils, page_start) {
-  ASSERT_EQ(0x0001000, page_start(0x0001000));
-  ASSERT_EQ(0x3002000, page_start(0x300222f));
-  ASSERT_EQ(0x6001000, page_start(0x6001fff));
+  ASSERT_EQ(0x0001000U, page_start(0x0001000));
+  ASSERT_EQ(0x3002000U, page_start(0x300222f));
+  ASSERT_EQ(0x6001000U, page_start(0x6001fff));
 }
 
 TEST(linker_utils, page_offset) {