introduce --with-assertions to build a release with assertions enabled

SConstruct

@@ -42,6 +42,12 @@ AddOption('--coverage',
             help='Build with coverage (gcov) support'
 )
 
+AddOption('--with-assertions',
+            dest='assertions',
+            action='store_true',
+            help='Build with assertions enabled (Default for a debug build)'
+)
+
 AddOption('--stack-protection',
             dest = 'stack_protection',
             action='store_true',
@@ -51,6 +57,7 @@ AddOption('--stack-protection',
 
 
 build_type = GetOption('build_type')
+assertions = GetOption('assertions')
 test_xml = GetOption('test_xml')
 prefix = GetOption('prefix')
 if not (build_type in ['debug', 'release']):
@@ -81,6 +88,7 @@ env.Append(CPPPATH = ['#include'])
 if build_type == 'release':
     env.Append(CFLAGS = ['-O2'])
 
+    if not assertions:
         #this will turn off assert()
         env.Append(CPPDEFINES = ['NDEBUG'])