Preferred executable for compiling a specific dialect of assembly language files. ASM<DIALECT> can be ASM, ASM_NASM, ASM_MASM or ASM-ATT. Will only be used by CMake on the first configuration to determine ASM<DIALECT> compiler, after which the value for ASM<DIALECT> is stored in the cache as CMAKE_ASM<DIALECT>_COMPILER. For subsequent configuration runs, the environment variable will be ignored in favor of CMAKE_ASM<DIALECT>_COMPILER.