[libc] Add a new suite called "libc-long-running-tests".

[sivachandra]

Summary

This suite is helpful is adding long running tests which take a long
time to finish that they can be run on the public builders. They
will probably be run on special builders in future.

libc/cmake/modules/LLVMLibCTestRules.cmake

function(add_libc_testsuite suite_name)
   add_dependencies(check-llvmlibc ${suite_name})
 endfunction(add_libc_testsuite)
 
 function(add_libc_exhaustive_testsuite suite_name)
   add_custom_target(${suite_name})
   add_dependencies(exhaustive-check-libc ${suite_name})
 endfunction(add_libc_exhaustive_testsuite)
 
+function(add_libc_long_running_testsuite suite_name)
+  add_custom_target(${suite_name})
+  add_dependencies(libc-long-running-tests ${suite_name})
+endfunction(add_libc_long_running_testsuite)
+
 # Rule to add a fuzzer test.
 # Usage
 #    add_libc_fuzzer(
 #      <target name>
 #      SRCS  <list of .cpp files for the test>
 #      HDRS  <list of .h files for the test>
 #      DEPENDS <list of dependencies>
 #    )

libc/test/CMakeLists.txt

 add_header_library(
   errno_setter_matcher
   HDRS
     ErrnoSetterMatcher.h
 )
 
 add_custom_target(check-libc)
 add_custom_target(check-llvmlibc)
 add_dependencies(check-libc check-llvmlibc)
 
 add_custom_target(exhaustive-check-libc)
+add_custom_target(libc-long-running-tests)
 
 add_subdirectory(src)
 add_subdirectory(utils)
 
 if(NOT LLVM_LIBC_FULL_BUILD)
   return()
 endif()
 
 add_subdirectory(config)
 add_subdirectory(integration)
 add_subdirectory(loader)