libtcc: minor adjustments

- use {B} to substitute tcc_lih_path (instead of \b)

- expand CONFIG_TCC_CRTPREFIX in CONFIG_TCC_LIBPATHS
  which fixes duplicate CONFIG_SYSROOT.

- put default CONFIG_SYSROOT ("") into tcc.h

- remove hack from commit db6fcce78f
  because $(tccdir)/include is already in sysincludes

- configure: error out for unrecognized options.

- win32/build-tcc.bat: put libtcc into base dir where it will
  find lib/include automatically, and build libtcc_test example.

tccpp.c

@@ -94,6 +94,11 @@ ST_FUNC void skip(int c)
     next();
 }
 
+ST_FUNC void expect(const char *msg)
+{
+    error("%s expected", msg);
+}
+
 /* ------------------------------------------------------------------------- */
 /* CString handling */
 static void cstr_realloc(CString *cstr, int new_size)