configure.ac: Fix improper join of include paths

acinclude.m4

@@ -10,6 +10,8 @@ AC_DEFUN([FIND_FILE], [
     IFS=:
     for ac__path in $3
     do
+        # IFS doesn't consolidate consecutive delimiters
+        ac__path=$(echo "$ac__path" | sed 's/:*$//')
         if test -r "$ac__path/$2" ; then
             IFS="$ac__save_ifs"
             AC_MSG_RESULT([$ac__path])

configure.ac

@@ -78,7 +78,7 @@ if test z$with_jni_headers != zcross ; then
     # Find jni_md.h
     JOIN_EACH([platform_include_paths], [$include_paths], [$with_jni_headers])
     FIND_FILE([jni_md_h_dir], [jni_md.h],
-            [$platform_include_paths $include_paths])
+            [$platform_include_paths:$include_paths])
     JNI_CFLAGS="\"-I$jni_h_dir\" \"-I$jni_md_h_dir\""
 else
     # For cross builds, we don't have the OpenJDK jni_md.h for the target