Don't change the C(XX)FLAGS provided by the user

This reveals a couple of unused-parameter warnings.

configure.ac

@@ -35,11 +35,11 @@ AC_ARG_ENABLE(debug,
     enable_debug=$enableval, enable_debug=no)
 
 if test "$enable_debug" = "yes" ; then
-    GCC_CFLAGS="$CFLAGS -g -D_DEBUG"
-    GCC_CXXFLAGS="$CXXFLAGS -g -D_DEBUG"
+    AM_CFLAGS="-g -D_DEBUG"
+    AM_CXXFLAGS="-g -D_DEBUG"
 else
-    GCC_CFLAGS="$CFLAGS -O2 -DNDEBUG"
-    GCC_CXXFLAGS="$CXXFLAGS -O2 -DNDEBUG"
+    AM_CFLAGS="-O2 -DNDEBUG"
+    AM_CXXFLAGS="-O2 -DNDEBUG"
 fi
 
 AM_PROG_LIBTOOL
@@ -49,8 +49,8 @@ AC_PROG_MAKE_SET
 AC_PROG_CXX([g++ c++ gpp aCC CC cxx cc++ cl FCC KCC RCC xlC_r xlC QCC])
 
 if test "$GCC" = "yes" ; then
-    CFLAGS="-Wall $GCC_CFLAGS"
-    CXXFLAGS="-Wall $GCC_CXXFLAGS"
+    AM_CFLAGS="$AM_CFLAGS -Wall -W"
+    AM_CXXFLAGS="$AM_CXXFLAGS -Wall -W"
 fi
 
 AC_PROG_CXXCPP
@@ -107,11 +107,14 @@ else
     AC_DEFINE(USE_PTHREADS,1,[define if pthread library is available])
     AC_DEFINE(_PTHREADS,1,[define for STL if pthread library is used])
     LIBS="$PTHREAD_LIBS $LIBS"
-    CFLAGS="$PTHREAD_CFLAGS $CFLAGS"
-    CXXFLAGS="$PTHREAD_CFLAGS $CXXFLAGS"
+    AM_CFLAGS="$PTHREAD_CFLAGS $AM_CFLAGS"
+    AM_CXXFLAGS="$PTHREAD_CFLAGS $AM_CXXFLAGS"
     CC="$PTHREAD_CC"
 fi
 
+AC_SUBST([AM_CFLAGS])
+AC_SUBST([AM_CXXFLAGS])
+
 AC_LANG(C++)
 
 AC_CXX_HAVE_SSTREAM
@@ -128,8 +131,6 @@ fi
 # ----------------------------------------------------------------------------
 BB_ENABLE_DOXYGEN
 
-PETI_PEDANTIC_GCC
-
 # Create files
 # ----------------------------------------------------------------------------
 

m4/PETI_PEDANTIC_GCC.m4

-dnl @synopsis PETI_PEDANTIC_GCC
-dnl
-dnl For development purposes, it is desirable to have autoconf
-dnl automatically enable warnings when compiling C or C++ sources. In
-dnl case the underlying compiler is a gcc, the appropriate flags are
-dnl "-Wall -pedantic". This macro will add them to $CFLAGS and
-dnl $CXXFLAGS if $CC is found to be a gcc.
-dnl
-dnl @author Peter Simons <simons@computer.org>
-dnl original version: peti_pedantic_gcc.m4,v 1.4 2000/12/31 10:18:09 simons
-dnl @version $Id: PETI_PEDANTIC_GCC.m4,v 1.4 2002/09/15 22:40:50 bastiaan Exp $
-
-AC_DEFUN([PETI_PEDANTIC_GCC],
-    [
-    if test "$GCC" = yes; then
- 	if test "$host" = x86-pc-nto-qnx; then
- 	    CFLAGS="$CXXFLAGS -Wno-unused -O0"
- 	    CXXFLAGS="$CXXFLAGS -Wno-unused -DLOG4SHIB_MISSING_INT64_OSTREAM_OP -O0"
-        else
-            case `$CXX --version` in
-                *2.97*) CFLAGS="$CFLAGS -Wall -Wno-unused -pedantic -D_ISOC99_SOURCE"
-                        CXXFLAGS="$CXXFLAGS -Wall -Wno-unused -pedantic -D_ISOC99_SOURCE" 
-                        ;;
-                *2.96*) CFLAGS="$CFLAGS -Wall -Wno-unused"
-                        CXXFLAGS="$CXXFLAGS -Wall -Wno-unused" 
-                        ;;
-	        *)      CFLAGS="$CFLAGS -Wall -Wno-unused -pedantic"
-                        CXXFLAGS="$CXXFLAGS -Wall -Wno-unused -pedantic"
-                        ;;
-            esac
-        fi
-    fi
-    ])