Eina log: Disable backtrace by default for dev builds

The EINA_LOG_BACKTRACE thing is aimed at production environments,
so we can extract a backtrace from a log file post-mortem, but not
for continuous development of EFL itself.

I know this should make a few people happy.

configure.ac

@@ -85,12 +85,17 @@ case "${build_profile}" in
 esac
 
 prefer_assert="no"
+eina_log_backtrace="yes"
 case "${build_profile}" in
    dev|debug)
      prefer_assert="yes"
+     eina_log_backtrace="no"
      ;;
 esac
 
+# Enable CRI & ERR backtrace by default for release but not for dev/debug
+AC_DEFINE_IF([EINA_LOG_BACKTRACE_ENABLE], [test "x${eina_log_backtrace}" = "xyes"], [1], [Default log level triggering backtraces])
+
 # TODO: add some build "profile" (server, full, etc...)
 
 AC_ARG_WITH([crypto],

src/lib/eina/eina_log.c

@@ -121,7 +121,12 @@ static Eina_Bool _disable_timing = EINA_TRUE;
 static int _abort_level_on_critical = EINA_LOG_LEVEL_CRITICAL;
 
 #ifdef EINA_LOG_BACKTRACE
-static int _backtrace_level = 1; // CRI & ERR by default
+// CRI & ERR by default in release mode, nothing in dev mode
+# ifndef EINA_LOG_BACKTRACE_ENABLE
+static int _backtrace_level = -1;
+# else
+static int _backtrace_level = 1;
+# endif
 #endif
 
 static Eina_Bool _threads_enabled = EINA_FALSE;