Revert "Include system/core/liblog/include instead of using symlinks"

Revert submission 1428983-no-log-header-symlinks

Reason for revert: Build breaks
Reverted Changes:
I248a2f045:Include system/core/liblog/include instead of usin...
Ic189e0f59:Remove logging symlinks from system/core/include

Change-Id: I9ee896f5fde36c879c182365295c1f5a5a39a76b