base: dlopen/dlsym for liblog when SDK_VER <= 29

libbase doesn't have to rely on dlopen/dlsym to use liblog's new symbols
when it is built for __ANDROID_SDK_VERSION__ > 29.

Bug: 150860940
Test: TARGET_BUILD_APPS="com.android.adbd com.android.resolv" m
      objdump -T ...shared_com.android.resolv/libbase.so | grep LIBLOG_R
        => should be none because resolv apex is targeting 29
      objdump -T ...shared_com.android.adbd/libbase.so | grep LIBLOG_R
        => should list all new symbols because adbd apex is targeting R
      objdump -T ...shared/libbase.so | grep LIBLOG_R
        => should list all new symbols

Merged-In: I7f7f16510d7637cd380fe35ea9ff3e804f38851d
Change-Id: I7f7f16510d7637cd380fe35ea9ff3e804f38851d
(cherry picked from commit 22207e65)