wbxml2: set correct LIB_SUFFIX for multilib

Fix QA issue when enable multilib:
ERROR: QA Issue: wbxml2: Files/directories were installed but not shipped in any package:
  /usr/lib
  /usr/lib/libwbxml2.so.0.0.17
  /usr/lib/libwbxml2.so
  /usr/lib/libwbxml2.so.0
  /usr/lib/.debug
  /usr/lib/pkgconfig
  /usr/lib/.debug/libwbxml2.so.0.0.17
  /usr/lib/pkgconfig/libwbxml2.pc
Please set FILES such that these items are packaged. Alternatively if they are unneeded, avoid installing them or delete them within do_install. [installed-vs-shipped]

Signed-off-by: Yi Zhao <yi.zhao@windriver.com>