process handling updated

Rev: src/configure.in:1.147
Rev: src/fdlib.c:1.4
Rev: src/main.c:1.30
Rev: src/mapping.c:1.25
Rev: src/mapping.h:1.5
Rev: src/modules/files/acconfig.h:1.6
Rev: src/modules/files/configure.in:1.37
Rev: src/modules/files/efuns.c:1.43
Rev: src/modules/files/file.c:1.65
Rev: src/modules/files/testsuite.in:1.8
Rev: src/signal_handler.c:1.17
Rev: src/signal_handler.h:1.4
Rev: src/stralloc.c:1.20