Undefined Reference in Mingw/Msys2 Build

[xaedes]

I get linker errors to undefined functions from regex library when compiling on Mingw/MSys2.

../../../libgpstk.a(UnixTime.cpp.obj):UnixTime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x5d): undefined reference to `regcomp'
../../../libgpstk.a(UnixTime.cpp.obj):UnixTime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x8f): undefined reference to `regerror'
../../../libgpstk.a(UnixTime.cpp.obj):UnixTime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x9e): undefined reference to `regfree'
../../../libgpstk.a(UnixTime.cpp.obj):UnixTime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x2a7): undefined reference to `regexec'
../../../libgpstk.a(UnixTime.cpp.obj):UnixTime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIlEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x435): undefined reference to `regfree'
../../../libgpstk.a(ANSITime.cpp.obj):ANSITime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x5d): undefined reference to `regcomp'
../../../libgpstk.a(ANSITime.cpp.obj):ANSITime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x8f): undefined reference to `regerror'
../../../libgpstk.a(ANSITime.cpp.obj):ANSITime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x9e): undefined reference to `regfree'
../../../libgpstk.a(ANSITime.cpp.obj):ANSITime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x2a7): undefined reference to `regexec'
../../../libgpstk.a(ANSITime.cpp.obj):ANSITime.cpp:(.text$_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_[_ZN5gpstk11StringUtils14formattedPrintIxEENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKS7_S9_S9_T_]+0x436): undefined reference to `regfree'