openpower-proc-control: use c++17

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

Change-Id: Ic782f5ca1a8435ecce99a92c5261d98eeac23647
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/configure.ac b/configure.ac
index e0534a9..743b210 100644
--- a/configure.ac
+++ b/configure.ac
@@ -10,7 +10,7 @@
 AC_PROG_MAKE_SET
 
 # 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