build: replace header checks with __has_include

See https://en.cppreference.com/w/cpp/preprocessor/include.

cmake/introspection.cmake

@@ -6,12 +6,6 @@ include(CheckCXXSourceCompiles)
 include(CheckCXXSymbolExists)
 include(CheckIncludeFileCXX)
 
-# The following HAVE_{HEADER}_H variables go to the bitcoin-build-config.h header.
-check_include_file_cxx(sys/prctl.h HAVE_SYS_PRCTL_H)
-check_include_file_cxx(sys/resources.h HAVE_SYS_RESOURCES_H)
-check_include_file_cxx(sys/vmmeter.h HAVE_SYS_VMMETER_H)
-check_include_file_cxx(vm/vm_param.h HAVE_VM_VM_PARAM_H)
-
 check_cxx_symbol_exists(O_CLOEXEC "fcntl.h" HAVE_O_CLOEXEC)
 check_cxx_symbol_exists(fdatasync "unistd.h" HAVE_FDATASYNC)
 check_cxx_symbol_exists(fork "unistd.h" HAVE_DECL_FORK)