Implement FIFO variant of scheduling of DSRs and make it the default. This is reworked patch originally suggested by Stefan Sommerfeld <sommerfeld@mikrom.com>. * cdl/interrupts.cdl (CYGIMP_KERNEL_INTERRUPTS_DSRS_LIST): make it cdl_component. * cdl/interrupts.cdl (CYGSEM_KERNEL_INTERRUPTS_DSRS_LIST_FIFO): new option for CYGIMP_KERNEL_INTERRUPTS_DSRS_LIST. * include/intr.hxx (class Cyg_Interrupt): new static variable dsr_list_tail. * src/intr/intr.cxx (call_pending_DSRs_inner): add CYGSEM_KERNEL_INTERRUPTS_DSRS_LIST_FIFO variant. (post_dsr): likewise. * tests/intr0.cxx: fix comments to match actual option names. * tests/kintr0.c: likewise.2006-03-27 Marco Cruz <marco@daruma.com.br>