Fix 'checking for ANSI C header files... no' with --enable-simulator
Fix 'checking for ANSI C header files... no' with --enable-simulator

It appears that if 'egrep' hasn't been searched for earlier, it is
searched for at the site of the first AC_CHECK_HEADERS (indirectly via
AC_EGREP_CPP), but this site happened to be conditional on RTS != sim.
By moving these tests to an unconditional site earlier in configure.in,
egrep is detected and ANSI C header files are found.

aschiffler/linuxcnc,aschiffler/linuxcnc,araisrobo/linuxcnc,narogon/linuxcnc,unseenlaser/linuxcnc,kinsamanka/machinekit,araisrobo/machinekit,ikcalB/linuxcnc-mirror,bobvanderlinden/machinekit,RunningLight/machinekit,unseenlaser/machinekit,ArcEye/MK-Qt5,araisrobo/linuxcnc,strahlex/machinekit,ArcEye/MK-Qt5,araisrobo/machinekit,cdsteinkuehler/linuxcnc,Cid427/machinekit,cdsteinkuehler/MachineKit,araisrobo/machinekit,bobvanderlinden/machinekit,bobvanderlinden/machinekit,ArcEye/machinekit-testing,strahlex/machinekit,ArcEye/machinekit-testing,ArcEye/machinekit-testing,ikcalB/linuxcnc-mirror,EqAfrica/machinekit,bmwiedemann/linuxcnc-mirror,kinsamanka/machinekit,unseenlaser/machinekit,cnc-club/linuxcnc,ianmcmahon/linuxcnc-mirror,kinsamanka/machinekit,strahlex/machinekit,cnc-club/linuxcnc,strahlex/machinekit,cdsteinkuehler/MachineKit,Cid427/machinekit,araisrobo/machinekit,cdsteinkuehler/MachineKit,ArcEye/machinekit-testing,Cid427/machinekit,mhaberler/machinekit,unseenlaser/machinekit,mhaberler/machinekit,mhaberler/machinekit,bobvanderlinden/machinekit,RunningLight/machinekit,jaguarcat79/ILC-with-LinuxCNC,unseenlaser/linuxcnc,ArcEye/MK-Qt5,EqAfrica/machinekit,bobvanderlinden/machinekit,araisrobo/machinekit,ianmcmahon/linuxcnc-mirror,jaguarcat79/ILC-with-LinuxCNC,ArcEye/MK-Qt5,mhaberler/machinekit,unseenlaser/linuxcnc,RunningLight/machinekit,ianmcmahon/linuxcnc-mirror,ikcalB/linuxcnc-mirror,jaguarcat79/ILC-with-LinuxCNC,cdsteinkuehler/linuxcnc,bobvanderlinden/machinekit,bmwiedemann/linuxcnc-mirror,ArcEye/machinekit-testing,strahlex/machinekit,cdsteinkuehler/MachineKit,ianmcmahon/linuxcnc-mirror,cdsteinkuehler/MachineKit,RunningLight/machinekit,aschiffler/linuxcnc,unseenlaser/machinekit,narogon/linuxcnc,araisrobo/machinekit,mhaberler/machinekit,EqAfrica/machinekit,ArcEye/MK-Qt5,kinsamanka/machinekit,cnc-club/linuxcnc,mhaberler/machinekit,aschiffler/linuxcnc,strahlex/machinekit,RunningLight/machinekit,bobvanderlinden/machinekit,ArcEye/MK-Qt5,ikcalB/linuxcnc-mirror,narogon/linuxcnc,bmwiedemann/linuxcnc-mirror,EqAfrica/machinekit,bobvanderlinden/machinekit,ArcEye/machinekit-testing,ikcalB/linuxcnc-mirror,kinsamanka/machinekit,araisrobo/machinekit,ArcEye/MK-Qt5,unseenlaser/machinekit,Cid427/machinekit,narogon/linuxcnc,unseenlaser/linuxcnc,bmwiedemann/linuxcnc-mirror,RunningLight/machinekit,ArcEye/MK-Qt5,Cid427/machinekit,ianmcmahon/linuxcnc-mirror,unseenlaser/machinekit,araisrobo/linuxcnc,ArcEye/machinekit-testing,ianmcmahon/linuxcnc-mirror,EqAfrica/machinekit,EqAfrica/machinekit,Cid427/machinekit,cdsteinkuehler/MachineKit,RunningLight/machinekit,bmwiedemann/linuxcnc-mirror,cdsteinkuehler/linuxcnc,cnc-club/linuxcnc,jaguarcat79/ILC-with-LinuxCNC,Cid427/machinekit,araisrobo/machinekit,araisrobo/linuxcnc,RunningLight/machinekit,unseenlaser/machinekit,cdsteinkuehler/linuxcnc,mhaberler/machinekit,unseenlaser/machinekit,cdsteinkuehler/linuxcnc,kinsamanka/machinekit,bmwiedemann/linuxcnc-mirror,cnc-club/linuxcnc,Cid427/machinekit,ikcalB/linuxcnc-mirror,kinsamanka/machinekit,EqAfrica/machinekit,EqAfrica/machinekit,jaguarcat79/ILC-with-LinuxCNC,araisrobo/linuxcnc,cnc-club/linuxcnc,aschiffler/linuxcnc,ikcalB/linuxcnc-mirror,araisrobo/machinekit,bmwiedemann/linuxcnc-mirror,cnc-club/linuxcnc,ArcEye/machinekit-testing,cdsteinkuehler/linuxcnc,unseenlaser/linuxcnc,mhaberler/machinekit,narogon/linuxcnc,kinsamanka/machinekit,strahlex/machinekit,ianmcmahon/linuxcnc-mirror