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.

tests2/36_array_initialisers.expect

@@ -0,0 +1,20 @@
+0: 12
+1: 34
+2: 56
+3: 78
+4: 90
+5: 123
+6: 456
+7: 789
+8: 8642
+9: 9753
+0: 12
+1: 34
+2: 56
+3: 78
+4: 90
+5: 123
+6: 456
+7: 789
+8: 8642
+9: 9753