fix clang wrappers build

The package is unconditionally built, so the wrappers should be
unconditional too, even if they don't get actually used without clang.
refer to icecream-users@googlegroups.com ML as the contact
mention the Linux3_ hack leading to nodes sometimes not being used
Linux3_ nodes may not compile on other nodes either, actually
Merge pull request #29 from llunak/master

fix clang wrappers build in specfile
prevent icerun-wrapped commands failing if path contains 'clang'

'icerun /path/contains/clang/some_command' would make compiler_is_clang()
return true, because analyze_program() keeps the path in compilerName()
for Lang_Custom CompileJob , unlike the other CompileJob kinds, which
store the compiler name without a path. This problem would show when
running this command, because analyse_argv() based on this would try
to add -fcolor-diagnostics to the command arguments in some circumstances.
Merge pull request #31 from llunak/master

Fix icerun-wrapped commands failing if the command's path contains 'clang' anywhere
remove unnecessary references to KDE to make icecream look KDE-specific
adjust references to icecream path

Now that it is usually /usr/lib/icecc/bin instead of /opt/icecream/bin .
sync the ccache section between README.md and the manpage

There should be something done about the duplication.
AC_CONFIG_HEADERS instead of obsolete and removed AM_CONFIG_HEADER

AC_CONFIG_HEADERS has been around for rather a while, so this should be safe.