configure.ac: Add --enable-sanitize and --enable-werror

this is "osmocom standard" these days, and is used by our CI scripts

configure.ac

@@ -49,6 +49,33 @@ AC_CHECK_LIB(m, atan2, [LIBS="$LIBS -lm"])
 dnl librealtime (for rtl_test)
 AC_CHECK_LIB(rt, clock_gettime, [LIBS="$LIBS -lrt"])
 
+AC_ARG_ENABLE(sanitize,
+		[AS_HELP_STRING([--enable-sanitize], [Compile with address sanitizer enabled], )],
+		[sanitize=$enableval], [sanitize="no"])
+if test x"$sanitize" = x"yes"
+then
+	CFLAGS="$CFLAGS -fsanitize=address -fsanitize=undefined"
+	CPPFLAGS="$CPPFLAGS -fsanitize=address -fsanitize=undefined"
+fi
+
+AC_ARG_ENABLE(werror,
+	[AS_HELP_STRING(
+		[--enable-werror],
+		[Turn all compiler warnings into errors, with exceptions:
+		 a) deprecation (allow upstream to mark deprecation without breaking builds);
+		 b) "#warning" pragmas (allow to remind ourselves of errors without breaking builds)
+		]
+	)],
+	[werror=$enableval], [werror="no"])
+if test x"$werror" = x"yes"
+then
+	WERROR_FLAGS="-Werror"
+	WERROR_FLAGS+=" -Wno-error=deprecated -Wno-error=deprecated-declarations"
+	WERROR_FLAGS+=" -Wno-error=cpp" # "#warning"
+	CFLAGS="$CFLAGS $WERROR_FLAGS"
+	CPPFLAGS="$CPPFLAGS $WERROR_FLAGS"
+fi
+
 # The following test is taken from WebKit's webkit.m4
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -fvisibility=hidden "