[Sanitizers] Remove clang_rt.sancov_{begin,end} on Solaris

[ro]

Summary

There's no point to manually create the __start___sancov_guards and __stop___sancov_guards
sections and labels on Solaris any longer. They were originally introduced in
https://reviews.llvm.org/D40899 and https://reviews.llvm.org/D40903.

• The Solaris 11.4 ld supports creating them out of the box.
• We already unconditionally use Solaris 11.4 features like the ld -z gnu-version-script-compat option and fully working .preinit_array support in compiler-rt.
• The current files don't assemble on SPARC because the assembler syntax may be different between /bin/as and GNU as.

Tested on amd64-pc-solaris2.11, ok for trunk?

[ro]

Ping? It's been a week and it's pretty trivial.

[ro]

Ping^2. It's been two weeks now and the patch (with its companion https://reviews.llvm.org/D63602) should be pretty simple.

compiler-rt/trunk/lib/sanitizer_common/CMakeLists.txt

 add_compiler_rt_object_libraries(RTSanitizerCommonSymbolizerNoHooks
   ${OS_OPTION}
   ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
   SOURCES ${SANITIZER_SYMBOLIZER_SOURCES}
   ADDITIONAL_HEADERS ${SANITIZER_IMPL_HEADERS}
   CFLAGS ${SANITIZER_NO_WEAK_HOOKS_CFLAGS}
   DEFS ${SANITIZER_COMMON_DEFINITIONS})
 
-if(OS_NAME MATCHES "SunOS")
-  # Solaris ld doesn't support the non-standard GNU ld extension of adding
-  # __start_SECNAME and __stop_SECNAME labels to sections whose names are
-  # valid C identifiers.  Instead we add our own definitions for the
-  # __sancov_guards section.
-  add_compiler_rt_object_libraries(SancovBegin
-    ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
-    SOURCES sancov_begin.S
-    CFLAGS ${SANITIZER_CFLAGS}
-    DEFS ${SANITIZER_COMMON_DEFINITIONS})
-
-  add_compiler_rt_runtime(clang_rt.sancov_begin
-    STATIC
-    ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
-    OBJECT_LIBS SancovBegin
-    CFLAGS ${SANITIZER_CFLAGS}
-    DEFS ${SANITIZER_COMMON_DEFINITIONS})
-
-  add_compiler_rt_object_libraries(SancovEnd
-    ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
-    SOURCES sancov_end.S
-    CFLAGS ${SANITIZER_CFLAGS}
-    DEFS ${SANITIZER_COMMON_DEFINITIONS})
-
-  add_compiler_rt_runtime(clang_rt.sancov_end
-    STATIC
-    ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
-    OBJECT_LIBS SancovEnd
-    CFLAGS ${SANITIZER_CFLAGS}
-    DEFS ${SANITIZER_COMMON_DEFINITIONS})
-endif()
-
 if(WIN32)
   add_compiler_rt_object_libraries(SanitizerCommonWeakInterception
     ${SANITIZER_COMMON_SUPPORTED_OS}
     ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
     SOURCES sanitizer_win_weak_interception.cc
     CFLAGS ${SANITIZER_CFLAGS} -DSANITIZER_DYNAMIC
     DEFS ${SANITIZER_COMMON_DEFINITIONS})
   add_compiler_rt_object_libraries(SancovWeakInterception

compiler-rt/trunk/lib/sanitizer_common/sancov_begin.S

-  .type   __start___sancov_guards,@object
-  .globl    __start___sancov_guards
-        .section        __sancov_guards,"aw",@progbits
-        .p2align        2
-__start___sancov_guards:

compiler-rt/trunk/lib/sanitizer_common/sancov_end.S

-  .type   __stop___sancov_guards,@object
-  .globl    __stop___sancov_guards
-        .section        __sancov_guards,"aw",@progbits
-        .p2align        2
-__stop___sancov_guards: