message: build: cleanup AX_CHECK_PREPROC_FLAG() usage
  There should be no functional change.
diff: @@ -362,9 +362,9 @@ if test "x$enable_debug" = xyes; then
  [AX_CHECK_COMPILE_FLAG([-g], [DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -g"], [], [$CXXFLAG_WERROR])],
  [$CXXFLAG_WERROR])
  - AX_CHECK_PREPROC_FLAG([-DDEBUG],[[DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG"]],,[[$CXXFLAG_WERROR]])
  - AX_CHECK_PREPROC_FLAG([-DDEBUG_LOCKORDER],[[DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG_LOCKORDER"]],,[[$CXXFLAG_WERROR]])
  - AX_CHECK_PREPROC_FLAG([-DABORT_ON_FAILED_ASSUME],[[DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DABORT_ON_FAILED_ASSUME"]],,[[$CXXFLAG_WERROR]])
  + AX_CHECK_PREPROC_FLAG([-DDEBUG], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG"], [], [$CXXFLAG_WERROR])
  + AX_CHECK_PREPROC_FLAG([-DDEBUG_LOCKORDER], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG_LOCKORDER"], [], [$CXXFLAG_WERROR])
  + AX_CHECK_PREPROC_FLAG([-DABORT_ON_FAILED_ASSUME], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DABORT_ON_FAILED_ASSUME"], [], [$CXXFLAG_WERROR])
  AX_CHECK_COMPILE_FLAG([-ftrapv], [DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -ftrapv"], [], [$CXXFLAG_WERROR])
  fi
  @@ -1280,7 +1280,7 @@ if test "x$enable_fuzz" = "xyes"; then
  use_zmq=no
  enable_fuzz_binary=yes
  - AX_CHECK_PREPROC_FLAG([-DABORT_ON_FAILED_ASSUME],[[DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DABORT_ON_FAILED_ASSUME"]],,[[$CXXFLAG_WERROR]])
  + AX_CHECK_PREPROC_FLAG([-DABORT_ON_FAILED_ASSUME], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DABORT_ON_FAILED_ASSUME"], [], [$CXXFLAG_WERROR])
  AC_MSG_CHECKING([whether main function is needed for fuzz binary])
  AX_CHECK_LINK_FLAG(
  @@ -1624,7 +1624,7 @@ if test "x$use_ccache" != "xno"; then
  AC_MSG_RESULT($use_ccache)
  if test "x$use_ccache" = "xyes"; then
  AX_CHECK_COMPILE_FLAG([-fdebug-prefix-map=A=B], [DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -fdebug-prefix-map=\$(abs_top_srcdir)=."], [], [$CXXFLAG_WERROR])
  - AX_CHECK_PREPROC_FLAG([-fmacro-prefix-map=A=B],[DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -fmacro-prefix-map=\$(abs_top_srcdir)=."],,[[$CXXFLAG_WERROR]])
  + AX_CHECK_PREPROC_FLAG([-fmacro-prefix-map=A=B], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -fmacro-prefix-map=\$(abs_top_srcdir)=."], [], [$CXXFLAG_WERROR])
  fi
  fi
  