bug 1399877 - Globally define DLL_PREFIX/DLL_SUFFIX. r=gps

Several source files use DLL_PREFIX/DLL_SUFFIX defines, and they all
set them in moz.build using `DEFINES`. This is problematic for the WSL build
because the quoting gets lost somewhere between bash and cl.exe. This patch
makes them set globally in moz.configure with `set_define`. There was an
existing global `MOZ_DLL_SUFFIX` define that was only used in one place, so
that has been removed in favor of simply `DLL_SUFFIX`.

MozReview-Commit-ID: 4ZQiqMK8Dgu

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extra : rebase_source : f85cbb4b9e6dc69881f312182cd4e37985baf22e