Bug 696910: Fix MINGW build.
Bug 696910: Fix MINGW build.

Additional flags/compiler settings required for successful
building on MINGW due to harfbuzz's use of strdup.

(cherry picked from commit 42bb12c41e4f06a0158abf916a0ff6d1ea4faa74)

TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,TamirEvan/mupdf