[shotwell] Use custom --enable-debug switch

[Jens Georg <jensgeorg src gnome org>]

commit e621cec664dedd62b0bc294b0bdacb0f8953f2ff
Author: Jens Georg <mail jensge org>
Date:   Wed Mar 15 22:32:08 2017 +0100

    Use custom --enable-debug switch
    
    Signed-off-by: Jens Georg <mail jensge org>

 configure.ac                |    9 ++-
 m4/ax_check_enable_debug.m4 |  124 -------------------------------------------
 2 files changed, 6 insertions(+), 127 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index ece805a..7b1d77a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -50,9 +50,12 @@ AX_GENERATE_CHANGELOG
 dnl ***********************************************************************
 dnl Add extra debugging with --enable-debug and --enable-compile-warnings
 dnl ***********************************************************************
-AX_CHECK_ENABLE_DEBUG([no],[]
-                      [G_DISABLE_ASSERT G_DISABLE_CHECKS G_DISABLE_CAST_CHECKS])
-
+AC_ARG_ENABLE(debug,
+              [AS_HELP_STRING([--enable-debug],[compile with debugging]),
+              [], enable_debug=no])
+enable_debug=${enable_debug-no}
+AS_IF([test "x$enable_debug" = "xyes"],[CFLAGS="${CFLAGS} -g -O0"])
+AM_CONDITIONAL([IS_NDEBUG], [test "x$enable_debug" != "xyes"])
 
 dnl ***********************************************************************
 dnl Internationalization