Fix OSS install script to build all deps at v2026.03.02.00 (#532)

[ahmadelyoussef]

Summary:

Context: https://fb.workplace.com/groups/604299349618684/permalink/30999815716306981/

Fixed with mostly help from Claude

---

Fix the UCacheBench open source install script so all Facebook OSS
dependencies (folly, fbthrift, CacheLib, mcrouter, etc.) build at
v2026.03.02.00.

Key changes:

1. CacheLib: switch from pinned commit to v2026.03.02.00 tag
   The old pinned commit (2812ee3) was incompatible with folly
   v2026.03.02.00 (missing Folly::folly_exception_tracer target).
   CacheLib v2026.03.02.00 already includes the fix for that (D92866330).

2. Patch CacheLib for fmt v11 compatibility
   CacheLib v2026.03.02.00's CombinedEntryStatus enum is not
   formattable with fmt v11.0.2. Add a format_as() function following
   the existing pattern in navy/common/Types.h. We patch rather than
   downgrading fmt because all Facebook OSS libs are version-locked —
   mixing versions causes cascading build failures.

3. Patch CacheLib to remove Folly::folly_exception_counter
   This CMake target was removed/made conditional in newer folly and is
   optional (debug exception counters, no functional impact). CacheLib
   v2026.03.02.00 still references it, so we strip it from CMakeLists.

4. Switch mcrouter from autotools to CMake build
   The old autotools approach (autoreconf/configure/make) didn't
   install headers properly or produce CMake config files, requiring
   manual workarounds (hardcoded library paths, extra include dirs).
   With CMake, find_package(mcrouter) works out of the box and handles
   transitive dependencies automatically.

5. Add mcrouter source include path to thrift generation
   The thrift compiler needs -I ${DEPS_DIR}/mcrouter to resolve
   mcrouter/lib/carbon/carbon.thrift includes when generating
   UCacheBench protocol code.

6. Add CMAKE_MODULE_PATH for fbcode_builder Find modules
   UCacheBench's CMake needs access to FindLibEvent.cmake and other
   custom Find modules from fbcode_builder when resolving mcrouter's
   transitive dependencies.

Reviewed By: charles-typ

Differential Revision: D97039942

[meta-codesync]

@ahmadelyoussef has exported this pull request. If you are a Meta employee, you can view the originating Diff in D97039942.