This fixes an error message when the file is not installed at all:
./autogen.sh: 67: [: Illegal number:
Turn the AX_CXX_COMPILE_STDCXX_11 errors into warnings though, since
it is (and should be) possible to build libsigrok (just the C library)
just fine, even without that macro or with an older version of it.
Add ACLOCAL_DIR setting and AM_PROG_AR macro for compiling with Homebrew
under Mac OS X.
Applies essentially the same change to
{libsigrok,libsigrokdecode,sigrok-cli}/{autogen.sh,configure.ac}
It may be that the same fix is needed for the other autogen.sh and/or
configure.ac files, but that hasn't been tested and therefore not in
this commit.
Rene Hopf
Uwe Hermann
Jens Steinhauser
Pekka Nikander
Bert Vermeulen