build: Add option to specify path to perl binary

plugins/meson.build

@@ -26,7 +26,7 @@ if get_option('with-lua') != 'false'
   subdir('lua')
 endif
 
-if get_option('with-perl')
+if get_option('with-perl') != 'false'
   subdir('perl')
 endif
 

plugins/perl/meson.build

@@ -25,7 +25,7 @@ if get_option('with-perl-legacy-api')
   perl_cflags += '-DOLD_PERL'
 endif
 
-perl = find_program('perl')
+perl = find_program(get_option('with-perl'))
 
 ret = run_command([perl, '-MExtUtils::Embed', '-e', 'ccopts'])
 if ret.returncode() != 0