Don't try to use constexpr for lambda variable

Apparently lambdas are non-literal types before C++17, and Clang errors
about this after r332286.

TBR=thakis

Bug: 843046
Change-Id: I9ec058e9e4e74e418d36d1875f7e51bf0d1165c1
Reviewed-on: https://chromium-review.googlesource.com/1059111Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558648}

chrome/browser/conflicts/enumerate_input_method_editors_win.cc

@@ -48,7 +48,7 @@ bool IsMicrosoftIme(const wchar_t* ime_guid) {
       L"{fa445657-9379-11d6-b41a-00065b83ee53}",
   };
 
-  constexpr auto comp = [](const wchar_t* lhs, const wchar_t* rhs) -> bool {
+  auto comp = [](const wchar_t* lhs, const wchar_t* rhs) -> bool {
     return base::CompareCaseInsensitiveASCII(lhs, rhs) == -1;
   };