Don't look for libunwind when BUILD_TESTING is off

Bug: 389897612
Change-Id: I4f9fec9a9ae8badf98922cf52aee526a155a725f
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/80187
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6e1592d..37f9c0a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -43,7 +43,8 @@
 
 set(INSTALL_ENABLED 1)
 
-if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND NOT CMAKE_CROSSCOMPILING)
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND NOT CMAKE_CROSSCOMPILING AND
+   BUILD_TESTING)
   find_package(PkgConfig QUIET)
   if (PkgConfig_FOUND)
     pkg_check_modules(LIBUNWIND libunwind-generic>=1.3.0)