Cross-compiling many types of test EXEs on Linux

ssokolow@monolith test_exes [master] % ./build.sh
 * Compiling for DOS with Dev86 (Real Mode)
 * Compiling for DOS with Pacific C (Real Mode)
 * Compiling for DOS with DJGPP (Protected Mode)
 * Compiling for com with OpenWatcom
 * Compiling for dos with OpenWatcom
 * Compiling for dos4g with OpenWatcom
 * Compiling for dos4gnz with OpenWatcom
 * Compiling for os2 with OpenWatcom
 * Compiling for os2v2 with OpenWatcom
 * Compiling for windows with OpenWatcom
 * Compiling for win386 with OpenWatcom
 * Compiling for win95 with OpenWatcom
 * Compiling for nt with OpenWatcom
 * Compiling for Win32 with MinGW
 * Compiling for Win64 with MinGW
 * Compiling hello.cs as exe on x86 with Mono
 * Compiling hello.cs as exe on x64 with Mono
 * Compiling hello.cs as exe on itanium with Mono
 * Compiling hello.cs as exe on arm with Mono
 * Attempting to rebuild test .lnk file
 * Building test JAR file
 * Building test SWF file (compressed)
 * Compiling native ELF64 binary with GCC for comparison
 * Compiling native ELF32 binary with GCC for comparison
 * Generating UPX-compressed copies
upx: hello_csharp_exe_arm.exe: CantPackException: can't pack new-exe
upx: hello_csharp_exe_itanium.exe: CantPackException: can't pack new-exe
upx: hello_csharp_exe_x64.exe: CantPackException: .NET files (win64/.net) are not yet supported
upx: hello_csharp_exe_x86.exe: CantPackException: .NET files (win32/.net) are not yet supported
    159914 ->     42628   26.66%   djgpp2/coff   hello_djgpp.upx.exe
    101820 ->     56252   55.25%    win32/pe     hello_mingw32.upx.exe
    123503 ->     63599   51.50%    win64/pe     hello_mingw64.upx.exe
     28334 ->     19132   67.52%    watcom/le    hello_owatcom_dos4g.upx.exe
upx: hello_owatcom_dos4gnz.exe: CantPackException: can't pack new-exe
      9126 ->      7247   79.41%     dos/exe     hello_owatcom_dos.upx.exe
     41039 ->     28751   70.06%    win32/pe     hello_owatcom_nt.upx.exe
upx: hello_owatcom_os2.exe: CantPackException: can't pack new-exe
upx: hello_owatcom_os2v2.exe: CantPackException: can't pack new-exe
upx: hello_owatcom_win386.exe: CantPackException: can't pack new-exe
     41039 ->     28751   70.06%    win32/pe     hello_owatcom_win95.upx.exe
upx: hello_owatcom_windows.exe: CantPackException: can't pack new-exe
      6848 ->      4528   66.12%     dos/exe     hello_pacific.upx.exe
      3616 ->      2539   70.22%     dos/com     hello_dev86.upx.com
      9214 ->      6947   75.40%     dos/com     hello_owatcom_com.upx.com
upx: hello_gcc.x86: NotCompressibleException
upx: hello_gcc.x86_64: NotCompressibleException
    159914 ->     40580   25.38%   djgpp2/coff   hello_djgpp.upx.coff.exe
 * Removing unnecessary execute bits