[Info-mtools] Undefined libiconv symbols

[Ryan Schmidt]

Hi, here's another problem when building mtools 4.0.25 (but also earlier 
versions) on macOS:


Undefined symbols for architecture x86_64:
  "_libiconv", referenced from:
      _getWcharCp in charsetConv.o
      _dos_to_wchar in charsetConv.o
      _safe_iconv in charsetConv.o
  "_libiconv_close", referenced from:
      _cp_open in charsetConv.o
      _getWcharCp in charsetConv.o
      _cp_close in charsetConv.o
  "_libiconv_open", referenced from:
      _cp_open in charsetConv.o
      _getWcharCp in charsetConv.o
      _wchar_to_native in charsetConv.o


If I add -Wl,-liconv to LDFLAGS when I run ./configure, that fixes it, but it 
would be nice if the build system would add that linker flag automatically. 
Presumably it works without this flag on some systems -- maybe iconv functions 
are in the standard C library on some non-Mac systems? -- so maybe you want to 
add a configure test to see if linking with libiconv is needed.