make: add __clang_analyzer__ to clang-tidy

We have code that acts slightly differently when the static analyzer is
running, so that it can produce more accurate diagnostics (e.g. less
false positives). It uses __clang_analyzer__ to detect the static
analyzer.

When the static analyzer is run via clang-tidy, __clang_analyzer__
doesn't get defined.

Bug: None
Test: WITH_TIDY=1 m. clang-tidy now acts as expected in code made for
the static analyzer

Change-Id: Ib2a815c0bd67553af465b64207bb480fb52cfaf8

core/binary.mk

@@ -1684,6 +1684,12 @@ ifneq (,$(filter 1 true,$(my_tidy_enabled)))
     ifeq ($(my_tidy_flags),)
       my_tidy_flags := $(call default_tidy_header_filter,$(LOCAL_PATH))
     endif
+
+    # We might be using the static analyzer through clang-tidy.
+    # https://bugs.llvm.org/show_bug.cgi?id=32914
+    ifneq ($(my_tidy_checks),)
+      my_tidy_flags += "-extra-arg-before=-D__clang_analyzer__"
+    endif
   endif
 endif