Don't look for terminfo libs when LLVM_ENABLE_TERMINFO=OFF

[haampie]

Summary

https://reviews.llvm.org/D85820 introduced a bug where LLVM_ENABLE_TERMINFO was set to true when the library was found, even when the user had set -DLLVM_ENABLE_TERMINFO=OFF.

[phosek]

LGTM

[srj]

Thanks. this fixes the issues I had with https://reviews.llvm.org/D85820 and Halide. LGTM.

[raj.khem]

I am still seeing build failures in NATIVE/llvm-config when I am cross building clang for say aarch64 on a x86_64 host. Even when I specify -DLLVM_ENABLE_TERMINFO=OFF, it still goes and pokes for these ncurses libs on build host and adds them to linker cmd. Since my target rootfs is set to not have these libs the final link fails to find -lterminfo rightly. Surprisingly, non NATIVE parts work ok and seem to respect LLVM_ENABLE_TERMINFO settings. Any insights ?

compiler-rt/cmake/config-ix.cmake

 check_library_exists(execinfo backtrace "" COMPILER_RT_HAS_LIBEXECINFO)
 
 # Look for terminfo library, used in unittests that depend on LLVMSupport.
 if(LLVM_ENABLE_TERMINFO STREQUAL FORCE_ON)
   set(MAYBE_REQUIRED REQUIRED)
 else()
   set(MAYBE_REQUIRED)
 endif()
+if(LLVM_ENABLE_TERMINFO)
   find_library(COMPILER_RT_TERMINFO_LIB NAMES terminfo tinfo curses ncurses ncursesw ${MAYBE_REQUIRED})
+endif()
 if(COMPILER_RT_TERMINFO_LIB)
   set(LLVM_ENABLE_TERMINFO 1)
 else()
   set(LLVM_ENABLE_TERMINFO 0)
 endif()
 
 if (ANDROID AND COMPILER_RT_HAS_LIBDL)
   # Android's libstdc++ has a dependency on libdl.

llvm/cmake/config-ix.cmake

if (NOT PURE_WINDOWS)
     else()
       set(HAVE_LIBEDIT 0)
     endif()
     if(LLVM_ENABLE_TERMINFO STREQUAL FORCE_ON)
       set(MAYBE_REQUIRED REQUIRED)
     else()
       set(MAYBE_REQUIRED)
     endif()
+    if(LLVM_ENABLE_TERMINFO)
       find_library(TERMINFO_LIB NAMES terminfo tinfo curses ncurses ncursesw ${MAYBE_REQUIRED})
+    endif()
     if(TERMINFO_LIB)
       set(LLVM_ENABLE_TERMINFO 1)
     else()
       set(LLVM_ENABLE_TERMINFO 0)
     endif()
 
     find_library(ICONV_LIBRARY_PATH NAMES iconv libiconv libiconv-2 c)
     set(LLVM_LIBXML2_ENABLED 0)