gbproxy: Change generic LOG messages so BVCI/NSEI fmt is consistent

We actually need to alter our compiler flags to avoid -Werror=trigraphs
creating trouble:

gb_proxy.c: In function ‘block_unblock_peer’:
gb_proxy.c:875:37: error: trigraph ??) ignored, use -trigraphs to enable [-Werror=trigraphs]
  875 |   LOGP(DGPRS, LOGL_ERROR, "BVC(%05u/??) Cannot find BSS\n",
      |

Fixes: SYS#5233
Change-Id: I93296353dd964602699480faae1248096e331c6a
diff --git a/configure.ac b/configure.ac
index 346e020..0ed36b8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -118,8 +118,8 @@
 CFLAGS="$saved_CFLAGS"
 AC_SUBST(SYMBOL_VISIBILITY)
 
-CPPFLAGS="$CPPFLAGS -Wall"
-CFLAGS="$CFLAGS -Wall"
+CPPFLAGS="$CPPFLAGS -Wall -Wno-trigraphs"
+CFLAGS="$CFLAGS -Wall -Wno-trigraphs"
 
 AX_CHECK_COMPILE_FLAG([-Werror=implicit], [CFLAGS="$CFLAGS -Werror=implicit"])
 AX_CHECK_COMPILE_FLAG([-Werror=maybe-uninitialized], [CFLAGS="$CFLAGS -Werror=maybe-uninitialized"])