Propagate -DPCRE_STATIC from pcre.BUILD to swig.BUILD

To fix a build error on Windows:
ERROR: C:/os/t/external/swig/BUILD.bazel:5:1: Linking of rule '@swig//:swig'
  failed (Exit 1120): link.exe failed: error executing command
misc.o : error LNK2019: unresolved external symbol __imp_pcre_compile
  referenced in function Swig_string_regex
...