misc: re-enable -Wno-unused-but-set-variable

There should be other ways around this.

Makefile.am

@@ -12,7 +12,7 @@ endif
 
 ACLOCAL_AMFLAGS = -I m4
 
-AM_CFLAGS = $(CWFLAGS) $(CSFLAGS)
+AM_CFLAGS = $(CWFLAGS)
 AM_CPPFLAGS = $(LIBFIDO2_CFLAGS) $(LIBCRYPTO_CFLAGS)
 if ENABLE_FUZZING
 AM_CPPFLAGS += -fsanitize=fuzzer-no-link

configure.ac

@@ -113,9 +113,6 @@ AX_CHECK_COMPILE_FLAG([-Wnull-dereference], [CWFLAGS="$CWFLAGS -Wnull-dereferenc
 AX_CHECK_COMPILE_FLAG([-Wshadow], [CWFLAGS="$CWFLAGS -Wshadow"], [], [$check_extra_flags])
 AX_CHECK_COMPILE_FLAG([-Wpointer-arith], [CWFLAGS="$CWFLAGS -Wpointer-arith"], [], [$check_extra_flags])
 
-AC_ARG_VAR([CSFLAGS], [Warning suppression flags])
-AX_CHECK_COMPILE_FLAG([-Wno-unused-but-set-variable], [CSFLAGS="-Wno-unused-but-set-variable"], [], [$check_extra_flags])
-
 AC_CONFIG_FILES([
   Makefile
   pamu2fcfg/Makefile
@@ -177,7 +174,6 @@ AC_MSG_NOTICE([Summary of build options:
   Compiler:            ${CC}
   CFLAGS:              ${CFLAGS}
   CWFLAGS:             ${CWFLAGS}
-  CSFLAGS:             ${CSFLAGS}
   Library types:       Shared=${enable_shared}, Static=${enable_static}
   LIBFIDO2 CFLAGS:     $LIBFIDO2_CFLAGS
   LIBFIDO2 LIBS:       $LIBFIDO2_LIBS

fuzz/Makefile.am

@@ -1,5 +1,5 @@
 # Copyright (C) 2020 Yubico AB - See COPYING
-AM_CFLAGS    = $(CWFLAGS) $(CSFLAGS) -fsanitize=fuzzer
+AM_CFLAGS    = $(CWFLAGS) -fsanitize=fuzzer
 AM_CPPFLAGS  = $(LIBFIDO2_CFLAGS) $(LIBCRYPTO_CFLAGS) -I$(srcdir)/..
 AM_CPPFLAGS += -D SCONFDIR='"@SCONFDIR@"'
 AM_LDFLAGS   = -no-install -fsanitize=fuzzer

tests/Makefile.am

@@ -2,7 +2,7 @@
 
 AM_TESTS_ENVIRONMENT = PAM_U2F_MODULE='$(top_builddir)/.libs/pam_u2f.so'
 
-AM_CFLAGS = $(CWFLAGS) $(CSFLAGS)
+AM_CFLAGS = $(CWFLAGS)
 AM_CPPFLAGS = -I$(srcdir)/..
 
 AM_LDFLAGS = -no-install