Meta: Increase fconstexpr-steps for Clang Lagom builds

Clang's default constexpr-steps limit is 1048576, which is not enough
for LibGfx's generation of the unicode bidirectional class lookup table
while GCC doesn't have any limit at all, so this patch increases the
limit to an arbitrarily larger value.

Meta/Lagom/CMakeLists.txt

@@ -8,7 +8,8 @@ else()
 endif()
 
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
- set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-overloaded-virtual -Wno-user-defined-literals")
+ # Clang's default constexpr-steps limit is 1048576(2^20), GCC doesn't have one
+ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-overloaded-virtual -Wno-user-defined-literals -fconstexpr-steps=16777216")
 
  if (ENABLE_ADDRESS_SANITIZER)
  add_definitions(-fsanitize=address -fno-omit-frame-pointer)