openpower-host-ipmi-flash: use c++17

Update configure.ac to choose the c++17 standard

Change-Id: I06d277597226f6f339c2467506963be521bdef84
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/configure.ac b/configure.ac
index 12e6b0f..548cccf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -31,7 +31,7 @@
 AS_IF([test "x$SDBUSPLUSPLUS" == "x"], AC_MSG_ERROR([Cannot find sdbus++]))
 
 # Checks for typedefs, structures, and compiler characteristics.
-AX_CXX_COMPILE_STDCXX(14, [noext])
+AX_CXX_COMPILE_STDCXX_17([noext])
 AX_APPEND_COMPILE_FLAGS([-Wall -Werror], [CXXFLAGS])
 
 # Checks for library functions.