Windows Package: Dependence on libgcc_s_sjlj-1.dll?

I have been working on a Windows binary package for slrn 1.0.3 with
great success so far. Compiled on a native Windows build using:

C:\Users\andrew>gcc --version
gcc (i686-win32-sjlj-rev1, Built by MinGW-W64 project) 6.2.0

The package will ship with dlls for:

 * libiconv
 * openssl

But a sticking point is a dependence on:

libgcc_s_sjlj-1.dll

which I would prefer not to ship with the package. For the life of me
I cannot see how to compile this statically rather than ship the dll.
Somewhere I need to add in a '-static-libgcc' option...

Any ideas?

Andrew
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