Add BPF target

This change adds the bpfel-unknown-none and bpfeb-unknown-none targets
which can be used to generate little endian and big endian BPF

src/tools/compiletest/src/runtest.rs

@@ -1835,6 +1835,7 @@ impl<'test> TestCx<'test> {
             || self.config.target.contains("nvptx")
             || self.is_vxworks_pure_static()
             || self.config.target.contains("sgx")
+            || self.config.target.contains("bpf")
         {
             // We primarily compile all auxiliary libraries as dynamic libraries
             // to avoid code size bloat and large binaries as much as possible
@@ -2310,6 +2311,10 @@ impl<'test> TestCx<'test> {
                 // No extra flags needed.
             }
 
+            Some("bpf-linker") => {
+                rustc.arg("-Clink-args=--emit=asm");
+            }
+
             Some(_) => self.fatal("unknown 'assembly-output' header"),
             None => self.fatal("missing 'assembly-output' header"),
         }

src/tools/compiletest/src/util.rs

@@ -48,6 +48,8 @@ const ARCH_TABLE: &[(&str, &str)] = &[
     ("armv7s", "arm"),
     ("asmjs", "asmjs"),
     ("avr", "avr"),
+    ("bpfeb", "bpfeb"),
+    ("bpfel", "bpfel"),
     ("hexagon", "hexagon"),
     ("i386", "x86"),
     ("i586", "x86"),