CDRIVER-4468 revert additional ccache checks (#1100)

* Revert "Do not elide find_package() if MONGO_USE_CCACHE is set (#1031)"

This reverts commit 237bcf8.

* Revert "Disable ccache by default for versions older than 3.4.3 (#1029)"

This reverts commit f55cc6a.

Author: kevinAlbs

build/cmake/CCache.cmake

@@ -8,42 +8,15 @@
     ON or OFF.
 ]]
 
+# Find and enable ccache for compiling
 find_program (CCACHE_EXECUTABLE ccache)
-
-# Enable ccache for compiling if not already configured.
-if (CCACHE_EXECUTABLE AND NOT DEFINED MONGO_USE_CCACHE)
+if (CCACHE_EXECUTABLE)
     message (STATUS "Found ccache: ${CCACHE_EXECUTABLE}")
-
-    execute_process (
-        COMMAND ${CCACHE_EXECUTABLE} --version | perl -ne "print $1 if /^ccache version (.+)$/"
-        OUTPUT_VARIABLE CCACHE_VERSION
-        OUTPUT_STRIP_TRAILING_WHITESPACE
-    )
-
-    # Assume `ccache --version` mentions a simple version string, e.g. "1.2.3".
-    # Permit patch number to be omitted, e.g. "1.2".
-    set (SIMPLE_SEMVER_REGEX "([0-9]+)\.([0-9]+)(\.([0-9]+))?")
-    string (REGEX MATCH "${SIMPLE_SEMVER_REGEX}" CCACHE_VERSION ${CCACHE_VERSION})
-
-    if (CCACHE_VERSION)
-        message (STATUS "Detected ccache version: ${CCACHE_VERSION}")
-    else ()
-        message (WARNING "Could not obtain ccache version from `ccache --version`. Defaulting to 0.1.0.")
-        set (CCACHE_VERSION 0.1.0)
-    endif ()
-
-    # Avoid spurious "ccache.conf: No such file or directory" errors due to ccache being invoked in parallel, which was patched in ccache version 3.4.3.
-    if (CCACHE_VERSION VERSION_LESS "3.4.3")
-        message (STATUS "Detected ccache version ${CCACHE_VERSION} is less than 3.4.3, which may lead to spurious failures when run in parallel. See https://github.com/ccache/ccache/issues/260 for more information.")
-        message (STATUS "Compiling with CCache disabled. Enable by setting MONGO_USE_CCACHE to ON")
-        option (MONGO_USE_CCACHE "Use CCache when compiling" OFF)
-    else ()
-        message (STATUS "Compiling with CCache enabled. Disable by setting MONGO_USE_CCACHE to OFF")
-        option (MONGO_USE_CCACHE "Use CCache when compiling" ON)
-    endif ()
-endif (CCACHE_EXECUTABLE AND NOT DEFINED MONGO_USE_CCACHE)
+    option (MONGO_USE_CCACHE "Use CCache when compiling" ON)
+endif ()
 
 if (MONGO_USE_CCACHE)
+    message (STATUS "Compiling with CCache enabled. Disable by setting MONGO_USE_CCACHE to OFF")
     set (CMAKE_CXX_COMPILER_LAUNCHER "${CCACHE_EXECUTABLE}")
     set (CMAKE_C_COMPILER_LAUNCHER "${CCACHE_EXECUTABLE}")
 endif ()