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.

tests2/17_enum.c

@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+enum fred
+{
+   a,
+   b,
+   c,
+   d,
+   e = 54,
+   f = 73,
+   g,
+   h
+};
+
+int main()
+{
+   enum fred frod;
+
+   printf("%d %d %d %d %d %d %d %d\n", a, b, c, d, e, f, g, h);
+   /* printf("%d\n", frod); */
+   frod = 12;
+   printf("%d\n", frod);
+   frod = e;
+   printf("%d\n", frod);
+
+   return 0;
+}
+
+/* vim: set expandtab ts=4 sw=3 sts=3 tw=80 :*/