Build libfuzzer libcxx-static with PIC

r356153 changed default build option of static libcxx to no PIC. We now
need to explicitly specify CMAKE_POSITION_INDEPENDENT_CODE to get PIC
libcxx.

Differential Revision: https://reviews.llvm.org/D65773

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@367943 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 852019d..3743db9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -143,6 +143,7 @@
     add_custom_libcxx(libcxx_fuzzer_${arch} ${LIBCXX_${arch}_PREFIX}
       CFLAGS ${TARGET_CFLAGS}
       CMAKE_ARGS -DCMAKE_CXX_COMPILER_WORKS=ON
+                 -DCMAKE_POSITION_INDEPENDENT_CODE=ON
                  -DLIBCXX_ABI_NAMESPACE=Fuzzer)
     target_compile_options(RTfuzzer.${arch} PRIVATE -isystem ${LIBCXX_${arch}_PREFIX}/include/c++/v1)
     add_dependencies(RTfuzzer.${arch} libcxx_fuzzer_${arch}-build)