message: depends: Prepend CPPFLAGS to C{,XX}FLAGS for CMake
  This is similar to how we do it for qt.mk.
diff: @@ -158,9 +158,9 @@ $(1)_autoconf += LDFLAGS="$$($(1)_ldflags)"
  endif
  $(1)_cmake=env CC="$$($(1)_cc)" \
  - CFLAGS="$$($(1)_cflags)" \
  + CFLAGS="$$($(1)_cppflags) $$($(1)_cflags)" \
  CXX="$$($(1)_cxx)" \
  - CXXFLAGS="$$($(1)_cxxflags)" \
  + CXXFLAGS="$$($(1)_cppflags) $$($(1)_cxxflags)" \
  cmake -DCMAKE_INSTALL_PREFIX:PATH="$$($($(1)_type)_prefix)"
  ifneq ($($(1)_type),build)
  ifneq ($(host),$(build))
  