Make Unicode license permissive again

This license text can be found [here](http://www.unicode.org/copyright.html).
The only statements regarding the changes being forbidden is

> Modification is not permitted with respect to this document. All copies of this document must be verbatim.

This statement forbids arbitrary license text modification, not the code patching.

build/conf/license.conf

@@ -180,9 +180,6 @@ LICENSES_UNATTRIBUTED= \
     Xfree86-1.0 \
     Xnet
 
-LICENSES_PATCHES_FORBIDDEN= \
-    Unicode
-
 LICENSES_FORBIDDEN= \
     AGPL-3.0-only \
     AGPL-3.0-or-later \
@@ -373,6 +370,7 @@ LICENSES_REQUIRE_CITATION= \
     Softsurfer \
     Spencer-94 \
     Sunpro \
+    Unicode \
     Unicode-DFS-2016 \
     Unicode-Icu-58 \
     Unicode-Mappings \
@@ -392,7 +390,6 @@ LICENSES_REQUIRE_CITATION= \
     zlib-acknowledgement \
     ZPL-2.1 \
     ${CUSTOM_LICENSE_LINUX_SYSCALL_NOTE} \
-    ${LICENSES_PATCHES_FORBIDDEN} \
 
 LICENSES_REQUIRE_CITATION_DYNAMIC= \
     LGPL \