PoCL/Windows: undefined symbol: _initterm_e

[maleadt]

This is somehow a recent error, possibly triggered by a Julia or CI worker upgrade.
As seen on #391 and #390 (which pins PoCL to v7.0 so hasn't been using a recently-built JLL):

      From worker 2:	ld.lld: error: undefined symbol: _initterm_e
      From worker 2:	>>> referenced by C:\mingw64\x86_64-w64-mingw32\lib\dllcrt2.o:(.text)
      From worker 2:	error: linker command failed with exit code 1 (use -v to see invocation)