compiler/embed: strip submod from d-r-p paths

Closes #2536

pkgs/compiler-test/tests/compiler/embed/embed-me39.rkt

@@ -0,0 +1,12 @@
+#lang racket/base
+
+(module+ main
+  (require (for-syntax racket/base)
+           racket/runtime-path)
+  (define-runtime-path license '(share "LICENSE-libscheme.txt"))
+  (with-output-to-file (build-path (find-system-path 'temp-dir) "stdout")
+    #:exists 'append
+    (lambda ()
+      (if (absolute-path? license)
+          (displayln "found license")
+          (displayln "not found")))))

pkgs/compiler-test/tests/compiler/embed/test.rkt

@@ -438,6 +438,14 @@
 	     (path->string (build-path (collection-path "tests" "compiler" "embed") "embed-me30.rkt")))
     (try-exe (mk-dest mred?) "Hello from a place!\n" mred?)
 
+    ;; raco exe on a module with a `main' submodule+ with a define-runtime-path within it
+    (system+ raco
+             "exe"
+	     "-o" (path->string (mk-dest mred?))
+	     (if mred? "--gui" "--")
+	     (path->string (build-path (collection-path "tests" "compiler" "embed") "embed-me39.rkt")))
+    (try-exe (mk-dest mred?) "found license\n" mred?)
+
     ;; raco exe --launcher
     (printf/flush ">>launcher\n")
     (system+ raco

racket/collects/compiler/embed.rkt

@@ -331,7 +331,7 @@
         actual-file-path
         use-source?))
 
-(define (mod-file m) (car m))
+(define (mod-file m) (strip-submod (car m)))
 (define (mod-mod-path m) (cadr m))
 (define (mod-code m) (caddr m))
 (define (mod-name m) (list-ref m 3))