Actually make fs_path_config / fs_path_config_from_file private

No one outside of libcutils is using these structs and we don't want
to leak them as they are private.

Test: build
Change-Id: I1c95564a9843c9155a333334008cbff7c7ff1f51
diff --git a/libcutils/fs_config.cpp b/libcutils/fs_config.cpp
index 5b5f2eb..897a169 100644
--- a/libcutils/fs_config.cpp
+++ b/libcutils/fs_config.cpp
@@ -39,6 +39,8 @@
 #include <private/android_filesystem_config.h>
 #include <utils/Compat.h>
 
+#include "fs_config.h"
+
 #ifndef O_BINARY
 #define O_BINARY 0
 #endif
@@ -47,6 +49,7 @@
 using android::base::StartsWith;
 
 #define ALIGN(x, alignment) (((x) + ((alignment)-1)) & ~((alignment)-1))
+#define CAP_MASK_LONG(cap_name) (1ULL << (cap_name))
 
 // Rules for directories.
 // These rules are applied based on "first match", so they