chore(cmake): set options changes as cache and with force

Without this, changes will not propergate to a parent if
toxcore is used as a subdirectory.

CMakeLists.txt

@@ -161,7 +161,7 @@ option(DHT_BOOTSTRAP "Enable building of DHT_bootstrap" ON)
 option(BOOTSTRAP_DAEMON "Enable building of tox-bootstrapd" ON)
 if(BOOTSTRAP_DAEMON AND WIN32)
   message(WARNING "Building tox-bootstrapd for Windows is not supported, disabling")
-  set(BOOTSTRAP_DAEMON OFF)
+  set(BOOTSTRAP_DAEMON OFF CACHE BOOL "" FORCE)
 endif()
 
 option(BUILD_FUZZ_TESTS "Build fuzzing harnesses" OFF)
@@ -177,18 +177,19 @@ include(Dependencies)
 
 if(MUST_BUILD_TOXAV)
   set(NO_TOXAV_ERROR_TYPE SEND_ERROR)
+  set(BUILD_TOXAV ON CACHE BOOL "" FORCE)
 else()
   set(NO_TOXAV_ERROR_TYPE WARNING)
 endif()
 
 if(BUILD_TOXAV)
   if(NOT OPUS_FOUND)
     message(${NO_TOXAV_ERROR_TYPE} "Option BUILD_TOXAV is enabled but required library OPUS was not found.")
-    set(BUILD_TOXAV OFF)
+    set(BUILD_TOXAV OFF CACHE BOOL "" FORCE)
   endif()
   if(NOT VPX_FOUND)
     message(${NO_TOXAV_ERROR_TYPE} "Option BUILD_TOXAV is enabled but required library VPX was not found.")
-    set(BUILD_TOXAV OFF)
+    set(BUILD_TOXAV OFF CACHE BOOL "" FORCE)
   endif()
 endif()
 
@@ -597,7 +598,7 @@ if(BOOTSTRAP_DAEMON)
     add_subdirectory(other/bootstrap_daemon)
   else()
     message(WARNING "Option BOOTSTRAP_DAEMON is enabled but required library LIBCONFIG was not found.")
-    set(BOOTSTRAP_DAEMON OFF)
+    set(BOOTSTRAP_DAEMON OFF CACHE BOOL "" FORCE)
   endif()
 endif()