This patch allows the build process to use the provided dependencies instead
of adding their source as CMake sub-directories (in which case "make install"
would install googletest's and googlebenchmark's libraries and headers).

diff --git a/CMakeLists.txt b/CMakeLists.txt
index bcae6b5..ff6710d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,7 +21,7 @@ IF(FXDIV_BUILD_TESTS)
 ENDIF()
 
 # ---[ Download deps
-IF(FXDIV_BUILD_TESTS AND NOT DEFINED GOOGLETEST_SOURCE_DIR)
+IF(FALSE)
   MESSAGE(STATUS "Downloading Google Test to ${CMAKE_BINARY_DIR}/googletest-source (define GOOGLETEST_SOURCE_DIR to avoid it)")
   CONFIGURE_FILE(cmake/DownloadGoogleTest.cmake "${CMAKE_BINARY_DIR}/googletest-download/CMakeLists.txt")
   EXECUTE_PROCESS(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
@@ -31,7 +31,7 @@ IF(FXDIV_BUILD_TESTS AND NOT DEFINED GOOGLETEST_SOURCE_DIR)
   SET(GOOGLETEST_SOURCE_DIR "${CMAKE_BINARY_DIR}/googletest-source" CACHE STRING "Google Test source directory")
 ENDIF()
 
-IF(FXDIV_BUILD_BENCHMARKS AND NOT DEFINED GOOGLEBENCHMARK_SOURCE_DIR)
+IF(FALSE)
   MESSAGE(STATUS "Downloading Google Benchmark to ${CMAKE_BINARY_DIR}/googlebenchmark-source (define GOOGLEBENCHMARK_SOURCE_DIR to avoid it)")
   CONFIGURE_FILE(cmake/DownloadGoogleBenchmark.cmake "${CMAKE_BINARY_DIR}/googlebenchmark-download/CMakeLists.txt")
   EXECUTE_PROCESS(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
@@ -54,7 +54,7 @@ INSTALL(FILES include/fxdiv.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 
 IF(FXDIV_BUILD_TESTS)
   # ---[ Build google test
-  IF(NOT TARGET gtest)
+  IF(FALSE)
     SET(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
     ADD_SUBDIRECTORY(
       "${GOOGLETEST_SOURCE_DIR}"
@@ -78,7 +78,7 @@ ENDIF()
 
 IF(FXDIV_BUILD_BENCHMARKS)
   # ---[ Build google benchmark
-  IF(NOT TARGET benchmark)
+  IF(FALSE)
     SET(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "" FORCE)
     ADD_SUBDIRECTORY(
       "${GOOGLEBENCHMARK_SOURCE_DIR}"
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<div class='path'>path: <a href='/guix/log/?id=75e7c094615f063b1018526c4c72838dd3173989'>root</a>/<a href='/guix/log/nix?id=75e7c094615f063b1018526c4c72838dd3173989'>nix</a>/<a href='/guix/log/nix/boost?id=75e7c094615f063b1018526c4c72838dd3173989'>boost</a>/<a href='/guix/log/nix/boost/throw_exception.hpp?id=75e7c094615f063b1018526c4c72838dd3173989'>throw_exception.hpp</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/nix/boost/throw_exception.hpp?id=75e7c094615f063b1018526c4c72838dd3173989&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>