compiler: add tests

This commit adds a very small test case. More importantly, it adds a
framework for other tests to be added in the future.

compiler/testdata/basic.ll

@@ -0,0 +1,13 @@
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv7m-none-eabi"
+
+define internal i32 @main.add(i32 %x, i32 %y, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %0 = add i32 %x, %y
+  ret i32 %0
+}
+
+define internal void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}