CMake Error:
ninja: error: build.ninja:1485: multiple rules generate ...
phonenumbers/metadata.h [-w dupbuild=err] 

Also Eliminate -Werror to fix sparc64 build

Fix build on i386

Index: cpp/CMakeLists.txt
--- cpp/CMakeLists.txt.orig
+++ cpp/CMakeLists.txt
@@ -32,7 +32,6 @@ set (TOOLS_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/too
 # Helper functions dealing with finding libraries and programs this library
 # depends on.
 
-include (FetchContent)
 include (GNUInstallDirs)
 
 function (print_error DESCRIPTION FILE)
@@ -102,34 +101,8 @@ endif ()
 # Find all the required libraries and programs.
 find_package(absl)
 
-if(NOT absl_FOUND)
-  # Overide abseil install rules for subprojects
-  set(ABSL_ENABLE_INSTALL ON)
-  
-  # Downloading the abseil sources at particular version to not catch up
-  # with its new build requirements like min C++14 is mandated in that lib.
-  FetchContent_Declare(
-      abseil-cpp
-      GIT_REPOSITORY  https://github.com/abseil/abseil-cpp.git
-      GIT_TAG         273292d
-  )
+find_package (absl REQUIRED)
 
-  # Building the abseil binaries
-  FetchContent_GetProperties(abseil-cpp)
-  if (NOT abseil-cpp_POPULATED)
-      FetchContent_Populate(abseil-cpp)
-  endif ()
-
-  if (NOT abseil-cpp_POPULATED)
-     message (FATAL_ERROR "Could not build abseil-cpp binaries.")
-  endif ()
-
-  # Safeguarding against any potential link errors as mentioned in
-  # https://github.com/abseil/abseil-cpp/issues/225
-  set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
-  add_subdirectory(${abseil-cpp_SOURCE_DIR} ${abseil-cpp_BINARY_DIR})
-endif()
-
 if (BUILD_TESTING)
   include (../tools/cpp/gtest.cmake)
   find_or_build_gtest ()
@@ -418,7 +391,7 @@ if (USE_ICU_REGEXP)
 endif ()
 
 if (NOT WIN32)
-  add_definitions ("-Wall -Werror")
+  add_definitions ("-Wall")
 endif ()
 
 include_directories ("src")
@@ -427,7 +400,7 @@ include_directories ("src")
 # Collate dependencies
 #----------------------------------------------------------------
 
-set (LIBRARY_DEPS ${ICU_LIB} ${PROTOBUF_LIB} absl::node_hash_set absl::strings absl::synchronization)
+set (LIBRARY_DEPS ${ICU_LIB} ${PROTOBUF_LIB} absl::check absl::log absl::node_hash_set absl::strings absl::synchronization)
 
 if (USE_BOOST)
   list (APPEND LIBRARY_DEPS ${Boost_LIBRARIES})
