Rearrange initial config checks: AC, AM, compilers, libtool, basic progs... #5214

Should be a more logical order of checks, from least dependent functions upwards. Helps with readibility also. Should address also #5195

@randy-waterhouse Does this actually fix #5195? I'd think that AM_INIT_AUTOMAKE would end up testing for gcc.

Also, many of those prog checks can just be dropped rather than moved, since libtool checks for them. I was going to PR that change at some point, but this seems like a good time. Looking quickly, I think we can drop:

AC_PROG_CC AC_PROG_CPP AC_PROG_CXXCPP AC_PROG_INSTALL AC_PROG_OBJC AC_PROG_LN_S AC_PROG_MKDIR_P AC_PROG_SED

#5195 should be fixed (AM_INIT_AUTOMAKE doesn't check for gcc) but if @paveljanik could test on his platform (SLES12, gcc added (no g++)) to make sure.

Also I have now removed those unusued or redundant AC_PROG_\ as you suggest, thanks.

looks good, assuming @paveljanik can confirm. Thanks.

No problem, I'll do so later today.

OK, I tested this:

• clean SUSE12 install, SDK added (no RPMs installed from it yet)
• checkout randy-waterhouse:config
• ./autogen.sh
• ./configure configure: error: C++ compiler cannot create executables GOOD
• zypper -n in gcc-c++
• ./configure checking for Berkeley DB C++ headers... no configure: error: libdb_cxx headers missing GOOD
• zypper -n in libdb-4_8-devel
• ./configure ... checking for dynamic linked boost test... no configure: error: No working boost sleep implementation found. GOOD (could be better, later...)
• zypper -n in boost-devel
• ./configure checking for SSL... no configure: error: openssl not found. GOOD
• zypper -n in openssl-devel
• ./configure OK
• make OK

To sum this: OK.

When building on minimal installation of SLES12, the needed RPM packages are:

gcc-c++ boost-devel libdb-4_8-devel openssl-devel

and are correctly reported by configure. Thanks!

Thanks for checking @paveljanik