[libc] Update include directory for libcMPCWrapper target when LIBC_MPC_INSTALL_PATH is set. (#124810)

Author: lntue

libc/cmake/modules/LLVMLibCCheckMPC.cmake

@@ -1,7 +1,7 @@
 if(LIBC_TESTS_CAN_USE_MPFR)
-  set(LLVM_LIBC_MPC_INSTALL_PATH "" CACHE PATH "Path to where MPC is installed (e.g. C:/src/install or ~/src/install)")
+  set(LIBC_MPC_INSTALL_PATH "" CACHE PATH "Path to where MPC is installed (e.g. C:/src/install or ~/src/install)")
 
-  if(LLVM_LIBC_MPC_INSTALL_PATH)
+  if(LIBC_MPC_INSTALL_PATH)
     set(LIBC_TESTS_CAN_USE_MPC TRUE)
   elseif(LIBC_TARGET_OS_IS_GPU OR LLVM_LIBC_FULL_BUILD)
     # In full build mode, the MPC library should be built using our own facilities,

libc/utils/MPCWrapper/CMakeLists.txt

@@ -17,6 +17,14 @@ if(LIBC_TESTS_CAN_USE_MPC)
     libc.src.__support.complex_type
     LibcTest.unit
   )
+  if(EXISTS ${LLVM_LIBC_MPFR_INSTALL_PATH})
+    target_include_directories(libcMPCWrapper PUBLIC ${LLVM_LIBC_MPFR_INSTALL_PATH}/include)
+    target_link_directories(libcMPCWrapper PUBLIC ${LLVM_LIBC_MPFR_INSTALL_PATH}/lib)
+  endif()
+  if(EXISTS ${LIBC_MPC_INSTALL_PATH})
+    target_include_directories(libcMPCWrapper PUBLIC ${LIBC_MPC_INSTALL_PATH}/include)
+    target_link_directories(libcMPCWrapper PUBLIC ${LIBC_MPC_INSTALL_PATH}/lib)
+  endif()
   target_include_directories(libcMPCWrapper PUBLIC ${LIBC_SOURCE_DIR})
   target_link_libraries(libcMPCWrapper PUBLIC libcMPCommon LibcFPTestHelpers.unit LibcTest.unit mpc)
 elseif(NOT LIBC_TARGET_OS_IS_GPU AND NOT LLVM_LIBC_FULL_BUILD)