Bug 1524079 - Try both host and target clang to find llvm-objdump. r=froydnj

When doing android cross builds, the target compiler might be clang,
but it might be the one from the NDK, which doesn't come with all the
tools. So `clang --print-prog-name=llvm-objdump` might not return
anything, when the system has a suffixed llvm-objdump, e.g.
llvm-objdump-6.0.

So it's better to check with the host compiler, which is likely clang
too. We still check with the target compiler, in the odd case where the
host and target compiler would be of different kinds (Windows
cross-builds).

Differential Revision: https://phabricator.services.mozilla.com/D18142

--HG--
extra : moz-landing-system : lando

moz.configure

@@ -584,14 +584,18 @@ set_config('MAKENSISU_FLAGS', nsis_flags)
 check_prog('7Z', ('7z', '7za'), allow_missing=True, when=target_is_windows)
 
 
-@depends(c_compiler, bindgen_config_paths)
-def llvm_objdump(c_compiler, bindgen_config_paths):
+@depends(host_c_compiler, c_compiler, bindgen_config_paths)
+def llvm_objdump(host_c_compiler, c_compiler, bindgen_config_paths):
     clang = None
-    if c_compiler and c_compiler.type == 'clang':
-        clang = c_compiler.compiler
-    elif c_compiler and c_compiler.type == 'clang-cl':
-        clang = os.path.join(os.path.dirname(c_compiler.compiler), 'clang')
-    elif bindgen_config_paths:
+    for compiler in (host_c_compiler, c_compiler):
+        if compiler and compiler.type == 'clang':
+            clang = compiler.compiler
+            break
+        elif compiler and compiler.type == 'clang-cl':
+            clang = os.path.join(os.path.dirname(compiler.compiler), 'clang')
+            break
+
+    if not clang and bindgen_config_paths:
         clang = bindgen_config_paths.clang_path
     llvm_objdump = 'llvm-objdump'
     if clang: