On cygwin, pysingular fails with shared library builds of Singular

[mkoeppe]

 g++ -shared -Wl,--enable-auto-image-base -L/opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/lib -Wl,-rpath,/opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/lib -O2 -g -march=native build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o -L/opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/lib -L/opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/lib/python3.8/config -L/usr/lib -lpython3.8 -o build/lib.cygwin-3.1.7-x86_64-3.8/PySingular.cpython-38-x86_64-cygwin.dll -lSingular
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:/tmp/pip-req-build-mnh0hhr7/SingularModule.cpp:103: undefined reference to `omSizeOfLargeAddr'
  build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o: in function `RunSingularCommand':
  /tmp/pip-req-build-mnh0hhr7/SingularModule.cpp:103:(.text+0x414): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `omSizeOfLargeAddr'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: /tmp/pip-req-build-mnh0hhr7/SingularModule.cpp:103: undefined reference to `omFreeSizeToSystem'
  /tmp/pip-req-build-mnh0hhr7/SingularModule.cpp:103:(.text+0x41f): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `omFreeSizeToSystem'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:/opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/include/omalloc/omInline.h:193: undefined reference to `omAlloc0Large'
  build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o: in function `_omalloc0':
  /opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/include/omalloc/omInline.h:193:(.text+0x471): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `omAlloc0Large'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: /opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/include/omalloc/omInline.h:193: undefined reference to `omAllocBinFromFullPage'
  /opt/sage-singular-84e068414b4a00e9ae1a11675e0cfc87014c88a7/include/omalloc/omInline.h:193:(.text+0x48c): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `omAllocBinFromFullPage'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o: in function `RunSingularCommand':
  /tmp/pip-req-build-mnh0hhr7/SingularModule.cpp:103: undefined reference to `omFreeToPageFault'
  /tmp/pip-req-build-mnh0hhr7/SingularModule.cpp:103:(.text+0x4a1): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `omFreeToPageFault'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:SingularModule.cpp:(.rdata$.refptr.PrintS_callback[.refptr.PrintS_callback]+0x0): undefined reference to `PrintS_callback'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:SingularModule.cpp:(.rdata$.refptr.WerrorS_callback[.refptr.WerrorS_callback]+0x0): undefined reference to `WerrorS_callback'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:SingularModule.cpp:(.rdata$.refptr.om_BinPageIndicies[.refptr.om_BinPageIndicies]+0x0): undefined reference to `om_BinPageIndicies'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:SingularModule.cpp:(.rdata$.refptr.om_MaxBinPageIndex[.refptr.om_MaxBinPageIndex]+0x0): undefined reference to `om_MaxBinPageIndex'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:SingularModule.cpp:(.rdata$.refptr.om_MinBinPageIndex[.refptr.om_MinBinPageIndex]+0x0): undefined reference to `om_MinBinPageIndex'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:SingularModule.cpp:(.rdata$.refptr.errorreported[.refptr.errorreported]+0x0): undefined reference to `errorreported'
  /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: build/temp.cygwin-3.1.7-x86_64-3.8/SingularModule.o:SingularModule.cpp:(.rdata$.refptr.om_Size2Bin[.refptr.om_Size2Bin]+0x0): undefined reference to `om_Size2Bin'
  collect2: error: ld returned 1 exit status

This would need additional changes in Singular similar to the ones in Singular/Singular#1055