Fix setjmps

I noticed this error when trying to compile with emscripten

In file included from ../../src/encode/SkPngEncoderImpl.cpp:39:
.../externals/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/csetjmp:39:6: error: "If libc++ starts defining <setjmp.h>, the __has_include check should move to libc++'s <setjmp.h>"
   39 | #    error "If libc++ starts defining <setjmp.h>, the __has_include check should move to libc++'s <setjmp.h>"
      |      ^
1 error generated.

Changing what we include seems to address this.

Change-Id: Ib2469bedf4137a7e2b07ee09740ea973d9d1485d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1328836
Commit-Queue: Kaylee Lubick <kjlubick@google.com>
Auto-Submit: Kaylee Lubick <kjlubick@google.com>
Reviewed-by: Julia Lavrova <jlavrova@google.com>