Do not install pkgconfig data files, pkg-config does not presently look at
/usr/lib/llvm/.../pkgconfig and putting them in /usr/lib*/pkgconfig would
cause collisions between slots.

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -66,11 +66,3 @@
   DESTINATION
     ${CMAKE_INSTALL_PREFIX}/include/LLVMSPIRVLib
 )
-
-configure_file(LLVMSPIRVLib.pc.in ${CMAKE_BINARY_DIR}/LLVMSPIRVLib.pc @ONLY)
-install(
-  FILES
-    ${CMAKE_BINARY_DIR}/LLVMSPIRVLib.pc
-  DESTINATION
-    ${CMAKE_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}/pkgconfig
-)