tests: Added numerous tests.

The tests are taken almost verbatim from the open source project PicoC. It can
be found at https://code.google.com/p/picoc/.

The tests range from very simple/trivial ones to more complicated. My view is
that the more tests the better. Without tests like this I was very reluctant to
make any changes to tcc for the fear of breaking things.

The tests pass on Win32, OSX, Linux x86 and x86_64. One or two tests fail on
each platform due to differences in the runtime library.

tests2/49_bracket_evaluation.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+struct point
+{
+   double x;
+   double y;
+};
+
+struct point point_array[100];
+
+int main()
+{
+   int my_point = 10;
+
+   point_array[my_point].x = 12.34;
+   point_array[my_point].y = 56.78;
+
+   printf("%f, %f\n", point_array[my_point].x, point_array[my_point].y);
+
+   return 0;
+}
+
+/* vim: set expandtab ts=4 sw=3 sts=3 tw=80 :*/