add a compatibilty test for the recent fixes and improvements

Just to double-check and ensure that we're still matching the
binary output of binutils-esp32ulp

Author: wnienhaus

tests/compat/fixes.S

@@ -0,0 +1,20 @@
+# This file tests various fixes to the assembler,
+# to ensure the binary output matches that of binutils.
+# a) support for left-aligned directives (e.g. .set without preceding whitespace)
+# b) a crash-fix related to data items in the .bss section
+# c) support for marking labels as global
+# d) support for upper case ULP opcode names
+#
+.set gpio, 2
+
+.bss
+
+counter:
+.long 0
+
+  .text
+  .global entry
+entry:
+  MOVE R1, gpio
+  WAIT 42
+  halt