[BOOT] Add the ISOMBR boot sector file in the ISO images (reactos#4988)

This completes our set of provided boot sectors offered in the
ReactOS ISOs that can help for remastering those without our whole
build environment.

Author: HBelusca

boot/freeldr/bootsect/CMakeLists.txt

@@ -40,6 +40,7 @@ if(ARCH STREQUAL "i386" OR ARCH STREQUAL "amd64")
     add_cd_file(TARGET ntfsvbr DESTINATION loader NO_CAB FILE ${CMAKE_CURRENT_BINARY_DIR}/ntfs.bin FOR bootcd regtest)
     add_cd_file(TARGET isoboot DESTINATION loader NO_CAB NOT_IN_HYBRIDCD FILE ${CMAKE_CURRENT_BINARY_DIR}/isoboot.bin FOR all hybridcd)
     add_cd_file(TARGET isobtrt DESTINATION loader NO_CAB NOT_IN_HYBRIDCD FILE ${CMAKE_CURRENT_BINARY_DIR}/isobtrt.bin FOR bootcd regtest)
+    add_cd_file(TARGET isombr DESTINATION loader NO_CAB NOT_IN_HYBRIDCD FILE ${CMAKE_CURRENT_BINARY_DIR}/isombr.bin FOR all hybridcd)
 elseif(ARCH STREQUAL "arm")
     add_custom_target(fat
         COMMAND exit 1