meson: look up cp and dtrace with find_program()

Avoid that meson prints a "Program xyz found" test once per
custom_target.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

pc-bios/keymaps/meson.build

@@ -38,6 +38,7 @@ if meson.is_cross_build() or 'CONFIG_XKBCOMMON' not in config_host
 else
   native_qemu_keymap = qemu_keymap
 endif
+cp = find_program('cp')
 
 t = []
 foreach km, args: keymaps
@@ -55,7 +56,7 @@ foreach km, args: keymaps
                        build_by_default: true,
                        input: km,
                        output: km,
-                       command: ['cp', '@INPUT@', '@OUTPUT@'],
+                       command: [cp, '@INPUT@', '@OUTPUT@'],
                        install: true,
                        install_dir: qemu_datadir / 'keymaps')
   endif

trace/meson.build

@@ -2,6 +2,7 @@
 specific_ss.add(files('control-target.c'))
 
 trace_events_files = []
+dtrace = find_program('dtrace', required: 'CONFIG_TRACE_DTRACE' in config_host)
 foreach dir : [ '.' ] + trace_events_subdirs
   trace_events_file = meson.source_root() / dir / 'trace-events'
   trace_events_files += [ trace_events_file ]
@@ -39,13 +40,13 @@ foreach dir : [ '.' ] + trace_events_subdirs
     trace_dtrace_h = custom_target(fmt.format('trace-dtrace', 'h'),
                                    output: fmt.format('trace-dtrace', 'h'),
                                    input: trace_dtrace,
-                                   command: [ 'dtrace', '-DSTAP_SDT_V2', '-o', '@OUTPUT@', '-h', '-s', '@INPUT@' ])
+                                   command: [ dtrace, '-DSTAP_SDT_V2', '-o', '@OUTPUT@', '-h', '-s', '@INPUT@' ])
     trace_ss.add(trace_dtrace_h)
     if host_machine.system() != 'darwin'
       trace_dtrace_o = custom_target(fmt.format('trace-dtrace', 'o'),
                                      output: fmt.format('trace-dtrace', 'o'),
                                      input: trace_dtrace,
-                                     command: [ 'dtrace', '-DSTAP_SDT_V2', '-o', '@OUTPUT@', '-G', '-s', '@INPUT@' ])
+                                     command: [ dtrace, '-DSTAP_SDT_V2', '-o', '@OUTPUT@', '-G', '-s', '@INPUT@' ])
       trace_ss.add(trace_dtrace_o)
     endif