[scudo] Build scudo_standalone on Android and Fuchsia.

[hctim]

Summary

This should be fine now, and is necessary for D102543.

[cryptoad]

I think Fuchsia doesn't need COMPILER_RT_HAS_AUXV since it's only used in Linux parts.

[hctim]

Relax AUXV requirement on Fuchsia.

[hctim]

Turns out there were some other things that are necessary to turn on the bots. This patch contains some of those things:

1. Remove -fno-emulated-tls from the scudo buildflags under Android. This can be removed because there should be no conflict with the platform TLS now that it's guarded by SCUDO_HAS_PLATFORM_TLS_SLOT.
2. Add some function declarations in some of the tests that are part of the NDK headers, but are guarded by NDK API level declarations.

A little more patching to do to get it working here, I think lit is still trying to enumerate the unit tests by executing --gtest_list_tests on the host rather than on the device, but I'm looking into it.

compiler-rt/cmake/config-ix.cmake

 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND CFI_SUPPORTED_ARCH)
   set(COMPILER_RT_HAS_CFI TRUE)
 else()
   set(COMPILER_RT_HAS_CFI FALSE)
 endif()
 
-#TODO(kostyak): add back Android & Fuchsia when the code settles a bit.
-if (SCUDO_STANDALONE_SUPPORTED_ARCH AND OS_NAME MATCHES "Linux" AND
-    COMPILER_RT_HAS_AUXV)
+if (SCUDO_STANDALONE_SUPPORTED_ARCH AND (
+      (OS_NAME MATCHES "Fuchsia") OR
+      (OS_NAME MATCHES "Linux|Android" AND COMPILER_RT_HAS_AUXV)))
   set(COMPILER_RT_HAS_SCUDO_STANDALONE TRUE)
 else()
   set(COMPILER_RT_HAS_SCUDO_STANDALONE FALSE)
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND SCUDO_SUPPORTED_ARCH AND
     OS_NAME MATCHES "Linux|Android|Fuchsia")
   set(COMPILER_RT_HAS_SCUDO TRUE)