build: ostree-gpg-verify-result.h is a public header, install it

Makefile-libostree-defines.am

@@ -27,6 +27,7 @@ libostree_public_headers = \
 	src/libostree/ostree-types.h \
 	src/libostree/ostree-repo-file.h \
 	src/libostree/ostree-diff.h \
+	src/libostree/ostree-gpg-verify-result.h \
 	src/libostree/ostree-sepolicy.h \
 	src/libostree/ostree-sysroot.h \
 	src/libostree/ostree-sysroot-upgrader.h \

Makefile-libostree.am

@@ -97,7 +97,6 @@ libostree_1_la_SOURCES = \
 	src/libostree/ostree-gpg-verifier.c \
 	src/libostree/ostree-gpg-verifier.h \
 	src/libostree/ostree-gpg-verify-result.c \
-	src/libostree/ostree-gpg-verify-result.h \
 	src/libostree/ostree-gpg-verify-result-private.h \
 	$(NULL)
 if USE_LIBARCHIVE