Don't install gtest

We link our tests against googletest, so there's no need to install it.

Bug: b/152606052
Change-Id: I8453882e8c999b563fab498fec6a34ee8235a273
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/60808
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 87dde98..5771526 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -692,6 +692,7 @@
 if(SWIFTSHADER_BUILD_TESTS)
     # For Win32, force gtest to match our CRT (shared)
     set(gtest_force_shared_crt TRUE CACHE BOOL "" FORCE)
+    set(INSTALL_GTEST FALSE CACHE BOOL "" FORCE)
     add_subdirectory(${THIRD_PARTY_DIR}/googletest EXCLUDE_FROM_ALL)
     # gtest finds python, which picks python 2 first, if present.
     # We need to undo this so that SPIR-V can later find python3.