meson: use override_find_program/override_dependency

Allow projects that use dtc as a subproject to find the tools and
library via find_program() and dependency().  This way, for those
projects there is no different between system dtc and subproject dtc.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20250612053829.1037412-1-pbonzini@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

libfdt/meson.build

@@ -40,6 +40,7 @@ libfdt_dep = declare_dependency(
   include_directories: libfdt_inc,
   link_with: libfdt,
 )
+meson.override_dependency('libfdt', libfdt_dep)
 
 if not wheel_only
   install_headers(

meson.build

@@ -118,6 +118,10 @@ if get_option('tools') and not wheel_only
   )
 endif
 
+foreach e: dtc_tools
+  meson.override_find_program(e.name(), e)
+endforeach
+
 if pylibfdt_enabled
   subdir('pylibfdt')
 endif