Remove libz.so from llvm dependencies

This doesn't seem to be needed to build LLVM in our configuration, and
it's not available in the Fuchsia prebuilt sysroot.

Bug: b/255822651
Change-Id: I53cb222c11dc60bf4d297bad229767653d9200f8
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/69368
Reviewed-by: Alexis Hétu <sugoi@google.com>
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Tested-by: John Bauman <jbauman@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Commit-Queue: John Bauman <jbauman@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
diff --git a/third_party/llvm-10.0/CMakeLists.txt b/third_party/llvm-10.0/CMakeLists.txt
index 3ea8d6a..bef287b 100644
--- a/third_party/llvm-10.0/CMakeLists.txt
+++ b/third_party/llvm-10.0/CMakeLists.txt
@@ -1279,7 +1279,7 @@
 
 # Add required libraries for LLVM
 if(LINUX OR APPLE)
-    target_link_libraries(llvm dl z)
+    target_link_libraries(llvm dl)
 endif()
 
 if(SWIFTSHADER_EMIT_COVERAGE)