Add defvars

Author: udzura

build.rs

@@ -22,6 +22,9 @@ fn main() {
         .define("MRB_INT64", "1")
         .define("PRISM_XALLOCATOR", "")
         .define("PRISM_BUILD_MINIMAL", "")
+        .define("PICORB_VM_MRUBYC", "")
+        .define("MRBC_ALLOC_LIBC", "")
+        .include("./vendor/include")
         .include("./vendor/mruby-compiler2/include")
         .include("./vendor/mruby-compiler2/lib/prism/include")
         .flag("-fPIC")

vendor/include/mrubyc.h

@@ -0,0 +1 @@
+// Dummy inclusion header