ocaml-base_bigstring: use legacysupport correctly

ocaml/ocaml-base_bigstring/Portfile

@@ -27,6 +27,10 @@ github.tarball_from archive
 # Use legacysupport to provide it.
 if {${os.platform} eq "darwin" && ${os.major} < 11} {
     patchfiles      patch-memmem.diff
+
+    post-patch {
+        reinplace "s|@PREFIX@|${prefix}|g" ${worksrcpath}/src/dune
+    }
 }
 
 depends_lib-append  port:ocaml-base \

ocaml/ocaml-base_bigstring/files/patch-memmem.diff

@@ -1,25 +1,9 @@
---- src/base_bigstring.h	2023-04-25 21:12:24.000000000 +0800
-+++ src/base_bigstring.h	2023-10-25 15:23:59.000000000 +0800
-@@ -3,6 +3,13 @@
-
- #include <caml/bigarray.h>
-
-+#ifdef __APPLE__
-+#include <AvailabilityMacros.h>
-+#if MAC_OS_X_VERSION_MAX_ALLOWED <= 1060
-+#include <LegacySupport/string.h>
-+#endif
-+#endif
-+
- /* Bigarray flags for creating a [Bigstring.t] */
- #define BASE_BIGSTRING_FLAGS (CAML_BA_CHAR | CAML_BA_C_LAYOUT)
-
 --- src/dune	2023-04-25 21:12:24.000000000 +0800
-+++ src/dune	2023-10-25 19:59:56.000000000 +0800
-@@ -1,3 +1,3 @@
++++ src/dune	2024-07-06 23:12:51.000000000 +0800
+@@ -1,3 +1,4 @@
  (library (name base_bigstring) (public_name base_bigstring)
-- (js_of_ocaml (javascript_files runtime.js)) (libraries base int_repr)
+  (js_of_ocaml (javascript_files runtime.js)) (libraries base int_repr)
 - (c_names base_bigstring_stubs) (preprocess (pps ppx_jane)))
 \ No newline at end of file
-+ (js_of_ocaml (javascript_files runtime.js)) (libraries base int_repr) (c_library_flags -lMacportsLegacySupport)
++ (c_flags -I@PREFIX@/include/LegacySupport) (c_library_flags -lMacportsLegacySupport)
 + (c_names base_bigstring_stubs) (preprocess (pps ppx_jane)))