[CMake] Link against ZLIB::ZLIB

[phosek]

Summary

This is the imported target that find_package(ZLIB) defines.

[compnerd]

Linking against the imported target should do the right thing and add interface headers too.

[phosek]

Closed by commit 00b3d49d3a86490f0596100b23cd2c3a49334c75.

[smeenai]

Can you check the output of llvm-config --system-libs after this? There's been some issues reported for that after the original change (https://github.com/llvm/llvm-project/commit/abb00753069554c538f3d850897373d093389945), such as https://bugs.llvm.org/show_bug.cgi?id=44780.

[foad]

Hi @phosek, my local check builds are failing with:

$ ninja check-llvm-bindings-go
[0/1] Running lit suite /home/jayfoad2/git/llvm-project/llvm/test/Bindings/Go
FAIL: LLVM :: Bindings/Go/go.test (1 of 1)
******************** TEST 'LLVM :: Bindings/Go/go.test' FAILED ********************
Script:
--
: 'RUN: at line 1';   /home/jayfoad2/llvm-debug/bin/llvm-go go=/usr/bin/go test llvm.org/llvm/bindings/go/llvm
--
Exit Code: 1

Command Output (stdout):
--
FAIL	llvm.org/llvm/bindings/go/llvm [build failed]

--
Command Output (stderr):
--
+ : 'RUN: at line 1'
+ /home/jayfoad2/llvm-debug/bin/llvm-go go=/usr/bin/go test llvm.org/llvm/bindings/go/llvm
# llvm.org/llvm/bindings/go/llvm
/usr/bin/ld.lld: error: unable to find library -lZLIB::ZLIB
clang: error: linker command failed with exit code 1 (use -v to see invocation)

--

********************

Testing Time: 12.58s
********************
Failing Tests (1):
    LLVM :: Bindings/Go/go.test

  Unexpected Failures: 1
FAILED: test/CMakeFiles/check-llvm-bindings-go 
cd /home/jayfoad2/llvm-debug/test && /usr/bin/python2.7 /home/jayfoad2/llvm-debug/./bin/llvm-lit -s -vv /home/jayfoad2/git/llvm-project/llvm/test/Bindings/Go
ninja: build stopped: subcommand failed.

Can you advise?

[chill]

We get bogus output from llvm-config:

$ ./bin/llvm-config --system-libs
-lZLIB::ZLIB -lrt -ldl -ltinfo -lpthread -lm

[srj]

We too get this bogus result from llvm-config (and it's breaking some of our builds). Please fix or revert.

llvm/lib/Support/CMakeLists.txt

 if(LLVM_ENABLE_ZLIB)
-  set(system_libs ${ZLIB_LIBRARY})
+  set(system_libs ZLIB::ZLIB)
 endif()
 
 if( MSVC OR MINGW )
   # libuuid required for FOLDERID_Profile usage in lib/Support/Windows/Path.inc.
   # advapi32 required for CryptAcquireContextW in lib/Support/Windows/Path.inc.
   set(system_libs ${system_libs} psapi shell32 ole32 uuid advapi32)
 elseif( CMAKE_HOST_UNIX )
   if( HAVE_LIBRT )