Remove include/backtrace symlink.

This requires a few other changes to support building libutils
properly. It does appear the windows versions of libutils is
referencing CallStack code, but it doesn't seem to cause any problems.
However, I removed those references completely for the windows build.

Also removed a few extra spaces that seem to have accumulated in the
RefBase.cpp.

Bug: 170465278

Test: Builds and libutils unit tests pass.
Change-Id: Ibeee7791b13636b34bdd592c5420fd91620f752a
diff --git a/libutils/Android.bp b/libutils/Android.bp
index dd9fea0..e53e89b 100644
--- a/libutils/Android.bp
+++ b/libutils/Android.bp
@@ -43,7 +43,13 @@
             header_libs: ["libbacktrace_headers"],
             export_header_lib_headers: ["libbacktrace_headers"],
         },
+        linux_glibc: {
+            header_libs: ["libbacktrace_headers"],
+            export_header_lib_headers: ["libbacktrace_headers"],
+        },
         linux_bionic: {
+            header_libs: ["libbacktrace_headers"],
+            export_header_lib_headers: ["libbacktrace_headers"],
             enabled: true,
         },
         windows: {