gnu: clang-runtime: Fix build issues against glibc 2.26.

* gnu/packages/patches/clang-runtime-asan-build-fixes.patch,
gnu/packages/patches/clang-runtime-esan-build-fixes.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/llvm.scm (clang-runtime-from-llvm): Add 'patches'
parameter and honor it.
(clang-runtime): Pass patch list.
(clang-runtime-3.9.1, clang-runtime-3.7, clang-runtime-3.6)
(clang-runtime-3.5): Likewise.

gnu/packages/patches/clang-runtime-asan-build-fixes.patch

@@ -0,0 +1,92 @@
+This patch works around build issues in libsanitizer.  Note that we carry the
+same patches for GCC since it includes the same libsanitizer.
+
+Work around this build error on glibc 2.26:
+
+  /tmp/guix-build-clang-runtime-3.5.2.drv-0/compiler-rt-3.5.2.src/lib/asan/asan_linux.cc: In function 'bool __asan::AsanInterceptsSignal(int)':
+  /tmp/guix-build-clang-runtime-3.5.2.drv-0/compiler-rt-3.5.2.src/lib/asan/asan_linux.cc:224:20: error: 'SIGSEGV' was not declared in this scope
+
+diff --git a/libsanitizer/asan/asan_linux.cc b/libsanitizer/asan/asan_linux.cc
+index c504168..59087b9 100644
+--- a/lib/asan/asan_linux.cc
++++ b/lib/asan/asan_linux.cc
+@@ -29,6 +29,7 @@
+ #include <dlfcn.h>
+ #include <fcntl.h>
+ #include <pthread.h>
++#include <signal.h>
+ #include <stdio.h>
+ #include <unistd.h>
+ #include <unwind.h>
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Now, work around this other error:
+
+  /tmp/guix-build-clang-runtime-3.5.2.drv-0/compiler-rt-3.5.2.src/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc: In function 'int __sanitizer::TracerThread(void*)':
+  /tmp/guix-build-clang-runtime-3.5.2.drv-0/compiler-rt-3.5.2.src/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc:239:22: error: aggregate 'sigaltstack handler_stack' has incomplete type and cannot be defined
+
+
+diff --git a/lib/sanitizer_common/sanitizer_linux.cc b/lib/sanitizer_common/sanitizer_linux.cc
+index 2cefa20..223d9c6 100644
+--- a/lib/sanitizer_common/sanitizer_linux.cc
++++ b/lib/sanitizer_common/sanitizer_linux.cc
+@@ -546,8 +546,7 @@ uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5) {
+ }
+ #endif
+ 
+-uptr internal_sigaltstack(const struct sigaltstack *ss,
+-                         struct sigaltstack *oss) {
++uptr internal_sigaltstack(const void *ss, void *oss) {
+   return internal_syscall(SYSCALL(sigaltstack), (uptr)ss, (uptr)oss);
+ }
+ 
+diff --git a/lib/sanitizer_common/sanitizer_linux.h b/lib/sanitizer_common/sanitizer_linux.h
+index 4497702..1594058 100644
+--- a/lib/sanitizer_common/sanitizer_linux.h
++++ b/lib/sanitizer_common/sanitizer_linux.h
+@@ -19,7 +19,6 @@
+ #include "sanitizer_platform_limits_posix.h"
+ 
+ struct link_map;  // Opaque type returned by dlopen().
+-struct sigaltstack;
+ 
+ namespace __sanitizer {
+ // Dirent structure for getdents(). Note that this structure is different from
+@@ -28,8 +27,7 @@ struct linux_dirent;
+ 
+ // Syscall wrappers.
+ uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count);
+-uptr internal_sigaltstack(const struct sigaltstack* ss,
+-                          struct sigaltstack* oss);
++uptr internal_sigaltstack(const void* ss, void* oss);
+ uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
+     __sanitizer_sigset_t *oldset);
+ void internal_sigfillset(__sanitizer_sigset_t *set);
+diff --git a/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc b/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
+index c919e4f..014162af 100644
+--- a/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
++++ b/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
+@@ -267,7 +267,7 @@ static int TracerThread(void* argument) {
+ 
+   // Alternate stack for signal handling.
+   InternalScopedBuffer<char> handler_stack_memory(kHandlerStackSize);
+-  struct sigaltstack handler_stack;
++  stack_t handler_stack;
+   internal_memset(&handler_stack, 0, sizeof(handler_stack));
+   handler_stack.ss_sp = handler_stack_memory.data();
+   handler_stack.ss_size = kHandlerStackSize;
+diff --git a/lib/tsan/tsan_platform_linux.cc b/lib/tsan/tsan_platform_linux.cc
+index 09cec5f..908f4fe 100644
+--- a/lib/tsan/rtl/tsan_platform_linux.cc
++++ b/lib/tsan/rtl/tsan_platform_linux.cc
+@@ -291,7 +291,7 @@ bool IsGlobalVar(uptr addr) {
+ int ExtractResolvFDs(void *state, int *fds, int nfd) {
+ #if SANITIZER_LINUX
+   int cnt = 0;
+-  __res_state *statp = (__res_state*)state;
++  struct __res_state *statp = (struct __res_state*)state;
+   for (int i = 0; i < MAXNS && cnt < nfd; i++) {
+     if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
+       fds[cnt++] = statp->_u._ext.nssocks[i];
+-- 
+2.9.3