[dav1d] should not depend on nasm on arm64

[BertalanD]

Is your feature request related to a problem? Please describe.

When building the dav1d port on arm64 (both AArch64 Linux and macOS), the build fails with the following if the nasm package is not installed:

CMake Error at scripts/cmake/vcpkg_find_acquire_program.cmake:166 (message):
  Could not find nasm.  Please install it via your package manager:

      sudo apt-get install nasm
Call Stack (most recent call first):
  buildtrees/versioning_/versions/dav1d/0349d1196602b2983b1171647b30b5a9379920c6/portfile.cmake:9 (vcpkg_find_acquire_program)
  scripts/ports.cmake:191 (include)

This dependency is used only in x86 builds of the port, otherwise it uses GAS or Clang's integrated assembler by invoking the C compiler binary.

Proposed solution

Similarly to ports like x264, the call to vcpkg_find_acquire_program(NASM) should be gated behind a check for x86:

vcpkg/ports/x264/portfile.cmake

Lines 58 to 75 in 7aeffc9

	vcpkg_list(SET EXTRA_ARGS)
	set(nasm_archs x86 x64)
	set(gaspp_archs arm arm64)
	if(NOT "asm" IN_LIST FEATURES)
	vcpkg_list(APPEND OPTIONS --disable-asm)
	elseif(NOT "$ENV{AS}" STREQUAL "")
	# Accept setting from triplet
	elseif(VCPKG_TARGET_ARCHITECTURE IN_LIST nasm_archs)
	vcpkg_find_acquire_program(NASM)
	transform_path_no_space(NASM)
	list(APPEND EXTRA_ARGS CONFIGURE_ENVIRONMENT_VARIABLES AS)
	set(AS "${NASM}") # for CONFIGURE_ENVIRONMENT_VARIABLES
	set(ENV{AS} "${NASM}") # for non-WIN32
	elseif(VCPKG_TARGET_ARCHITECTURE IN_LIST gaspp_archs AND VCPKG_TARGET_IS_WINDOWS AND VCPKG_HOST_IS_WINDOWS)
	vcpkg_find_acquire_program(GASPREPROCESSOR)
	list(FILTER GASPREPROCESSOR INCLUDE REGEX gas-preprocessor)
	file(INSTALL "${GASPREPROCESSOR}" DESTINATION "${SOURCE_PATH}/tools" RENAME "gas-preprocessor.pl")
	endif()

dav1d similarly supports gaspp when targeting arm/arm64 Windows.

Describe alternatives you've considered

No response

Additional context

No response

[github-actions]

From the log:

  Could not find nasm.  Please install it via your package manager:

      sudo apt-get install nasm

[BertalanD]

I think this issue was auto-closed mistakenly.

Yes, I can read the error message, and have installed nasm to make it go away locally. But that doesn't change the fact that this dependency is unnecessary (and useless) on arm.