implement ConfigureOp#check_d_import

build_tests/configure/check_d_import_failure.rb

@@ -0,0 +1,3 @@
+configure do
+  check_d_import "not.found"
+end

build_tests/configure/check_d_import_no_fail.rb

@@ -0,0 +1,3 @@
+configure do
+  check_d_import "not.found", fail: false
+end

build_tests/configure/check_d_import_success.rb

@@ -0,0 +1,3 @@
+configure do
+  check_d_import "std.stdio"
+end