Port error.h from svn -r3438 + minor changes (error_test does not pass!)

In svn -r3438 error_test is not used as a test program and it does not pass.

 EXTRA_DIST += \

         benchmark/Makefile

 if WANT_BENCHMARK

 noinst_HEADERS +=

 noinst_PROGRAMS +=

 endif WANT_BENCHMARK