Remove support for obsolete bionic versions.

The current Android NDK defines __BIONIC_HAVE_UCONTEXT_T for all
architecures, so the old paths are no longer needed.

Bug: chromium:437330
Change-Id: I6314971e9ee1d78c4b73f8c1b37af7aa6f419b71
Reviewed-on: https://chromium-review.googlesource.com/1252282Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56322}

src/base/platform/platform-linux.cc

@@ -27,14 +27,6 @@
 #include <sys/types.h>  // mmap & munmap
 #include <unistd.h>     // sysconf
 
-// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
-// Old versions of the C library <signal.h> didn't define the type.
-#if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
-    (defined(__arm__) || defined(__aarch64__)) &&                 \
-    !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
-#include <asm/sigcontext.h>  // NOLINT
-#endif
-
 #include <cmath>
 
 #undef MAP_TYPE

src/libsampler/sampler.cc

@@ -21,20 +21,12 @@
 #include <mach/mach.h>
 // OpenBSD doesn't have <ucontext.h>. ucontext_t lives in <signal.h>
 // and is a typedef for struct sigcontext. There is no uc_mcontext.
-#elif(!V8_OS_ANDROID || defined(__BIONIC_HAVE_UCONTEXT_T)) && !V8_OS_OPENBSD
+#elif !V8_OS_OPENBSD
 #include <ucontext.h>
 #endif
 
 #include <unistd.h>
 
-// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
-// Old versions of the C library <signal.h> didn't define the type.
-#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
-    (defined(__arm__) || defined(__aarch64__)) && \
-    !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
-#include <asm/sigcontext.h>  // NOLINT
-#endif
-
 #elif V8_OS_WIN || V8_OS_CYGWIN
 
 #include "src/base/win32-headers.h"