Use CMAKE_POSITION_INDEPENDENT_CODE instead of -fPIC

CMakeLists.txt

@@ -50,6 +50,7 @@ if(MSVC)
   set(CMAKE_STATIC_LINKER_FLAGS ${MSVC_LINKER_FLAGS})
 endif()
 
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH}" "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 include(GtsamMakeConfigFile)
 include(GNUInstallDirs)

cmake/GtsamBuildTypes.cmake

@@ -130,7 +130,6 @@ else()
 
   set(GTSAM_COMPILE_OPTIONS_PRIVATE_COMMON
     -Wall                                          # Enable common warnings
-    -fPIC                                          # ensure proper code generation for shared libraries
     $<$<CXX_COMPILER_ID:GNU>:-Wreturn-local-addr -Werror=return-local-addr>            # Error: return local address
     $<$<CXX_COMPILER_ID:Clang>:-Wreturn-stack-address   -Werror=return-stack-address>  # Error: return local address
     $<$<CXX_COMPILER_ID:Clang>:-Wno-weak-template-vtables>  # TODO(dellaert): don't know how to resolve

gtsam/3rdparty/metis/libmetis/CMakeLists.txt

@@ -3,7 +3,6 @@ include_directories(.)
 # Find sources.
 file(GLOB metis_sources *.c)
 # Build libmetis.
-add_definitions(-fPIC)
 add_library(metis-gtsam ${METIS_LIBRARY_TYPE} ${GKlib_sources} ${metis_sources})
 if(UNIX)
   target_link_libraries(metis-gtsam m)