ADSupport does not generate correct static mingw libs for GraphicsMagick

[Engbretson]

If one wishes to use the NDFileMagick plugin with at least mingw x64, certain library references are unresolved.
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x2a1): undefined reference to __imp__ZN6Magick5ImageC1Ev' /mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x3ba): undefined reference to __imp__ZN6Magick5Image4typeEN9MagickLib9ImageTypeE'
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x3ed): undefined reference to __imp__ZN6Magick5Image4readEjjRKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEN9MagickLib11StorageTypeEPKv' /mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x405): undefined reference to __imp__ZN6Magick5Image7channelEN9MagickLib11ChannelTypeE'
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x412): undefined reference to __imp__ZN6Magick5Image7qualityEj' /mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x41f): undefined reference to __imp__ZN6Magick5Image5depthEj'
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x42a): undefined reference to __imp__ZN6Magick5Image12compressTypeEN9MagickLib15CompressionTypeE' /mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x48c): undefined reference to __imp__ZN6Magick5Image5writeERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE'
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x4ad): undefined reference to __imp__ZN6Magick5ImageD1Ev' /mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x5d1): undefined reference to __imp__ZN6Magick5ImageD1Ev'
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x726): undefined reference to __imp__ZN6Magick5ImageC1Ev' /mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x7a1): undefined reference to __imp__ZN6Magick16InitializeMagickEPKc'
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text+0x7fc): undefined reference to __imp__ZN6Magick5ImageD1Ev' /mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text$_ZN12NDFileMagickD1Ev[_ZN12NDFileMagickD1Ev]+0x2e): undefined reference to __imp__ZN6Magick5ImageD1Ev'
/mnt/c/epics71/areaDetector-3-2/ADCore-3-2/lib/windows-x64-mingw/NDPlugin.lib(NDFileMagick.o):NDFileMagick.cpp:(.text$_ZN12NDFileMagickD0Ev[_ZN12NDFileMagickD0Ev]+0x2e): undefined reference to `__imp__ZN6Magick5ImageD1Ev'
collect2: error: ld returned 1 exit status
This is due to the include.h file in the Magick++ directory being

#if (defined(WIN32) || defined(WIN64)) && !defined (CYGWIN) //&& !defined(MINGW32)

So by default all flavors of mingw get

MagickDLLDecl __declspec(dllexport)

Even when your building static libraries

Making this change seems to work for me, but only tested with the x64 version of mingw

#if (defined(WIN32) || defined(WIN64)) && !defined (CYGWIN) && !defined(MINGW32) && !defined(MINGW64)

Not tested to see what happens if shared libraries are actually required,