Remove CORE_UTIL_EXPORT

[ Merge of http://go/wvgerrit/155070 ]

These functions are internal utilities and should not be exported from
our library.  IIRC, this was added to aid in Windows tests, but this is
no longer needed.

Bug: 236317198
Test: build_and_run_all_unit_tests.sh
Change-Id: I19beb35a15f0f87dc8f968e1dd5302aed9463e54

libwvdrmengine/cdm/util/include/util_common.h

@@ -9,23 +9,11 @@
 
 #ifdef _WIN32
 
-#  ifdef CORE_UTIL_IMPLEMENTATION
-#    define CORE_UTIL_EXPORT __declspec(dllexport)
-#  else
-#    define CORE_UTIL_EXPORT __declspec(dllimport)
-#  endif
-
 #  define CORE_UTIL_IGNORE_DEPRECATED
 #  define CORE_UTIL_RESTORE_WARNINGS
 
 #else
 
-#  ifdef CORE_UTIL_IMPLEMENTATION
-#    define CORE_UTIL_EXPORT __attribute__((visibility("default")))
-#  else
-#    define CORE_UTIL_EXPORT
-#  endif
-
 #  ifdef __GNUC__
 #    define CORE_UTIL_IGNORE_DEPRECATED \
       _Pragma("GCC diagnostic push")    \