Remove kv_engine-specific CMAKE_MINIMUM_REQUIRED

We can just inherit the top-level make (tlm)'s setting; which avoids
having to maintain the minimum for each project.

This fixes the following CMake warning:

    CMake Warning (dev) at kv_engine/engines/ep/tests/CMakeLists.txt:120 (target_sources):
      Policy CMP0076 is not set: target_sources() command converts relative paths
      to absolute.  Run "cmake --help-policy CMP0076" for policy details.  Use
      the cmake_policy command to set the policy and suppress this warning.

      An interface source of target "ep-engine_ep_unit_tests" has a relative
      path.

Note: Moving from CMake minimum 3.2 to 3.15 (current in top-level)
changes policy CMP0065[1], which doesn't export symbols from
executables by default. To allow the breakpad test symbol
recursive_crash_function to still be visible we need to set
ENABLE_EXPORTS on memcached.

[1]: https://cmake.org/cmake/help/latest/policy/CMP0065.html

Change-Id: I2b70d9acfa260c30abcbd6c6d5acc8788ecda188
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/155206
Tested-by: Build Bot <[email protected]>
Reviewed-by: Trond Norbye <[email protected]>

Author: daverigby

CMakeLists.txt

@@ -1,4 +1,3 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 3.2)
 PROJECT(Memcached LANGUAGES C CXX)
 
 INCLUDE(CheckCSourceCompiles)

daemon/CMakeLists.txt

@@ -230,6 +230,15 @@ ADD_EXECUTABLE(memcached main.cc)
 TARGET_LINK_LIBRARIES(memcached memcached_daemon)
 add_sanitizers(memcached)
 kv_enable_pch(memcached)
+# Allow 'memcached' to export symbols - i.e. symbols marked as
+# MEMCACHED_PUBLIC_API / MEMCACHED_PUBLIC_CLASS should marked as externally
+# visible in the symbol table.
+# We don't strictly _need_ this setting, memcached is now statically linked
+# and hence no symbols need to be visible externally for the product, however
+# we do still mark a test function (recursive_crash_function in crash_engine)
+# As MEMCACHED_PUBLIC_API to verify Breakpad is working correctly and it's
+# valuble to still be able to see that symbol.
+set_target_properties(memcached PROPERTIES ENABLE_EXPORTS TRUE)
 
 INSTALL(TARGETS memcached
         RUNTIME DESTINATION bin)