cmake: put the DEFINED check in the same if-statement

pkgs/development/tools/build-managers/cmake/001-search-path.diff

@@ -12,7 +12,7 @@ index b9381c3d7d..5e944640b5 100644
    # CMake install location
    "${_CMAKE_INSTALL_DIR}"
    )
-@@ -47,48 +44,50 @@ endif()
+@@ -47,48 +44,49 @@ endif()
 
  # Non "standard" but common install prefixes
  list(APPEND CMAKE_SYSTEM_PREFIX_PATH
@@ -22,16 +22,15 @@ index b9381c3d7d..5e944640b5 100644
    )
 
  # List common include file locations not under the common prefixes.
-+if(DEFINED ENV{NIX_CC})
-+  if(IS_DIRECTORY "$ENV{NIX_CC}"
-+    AND EXISTS "$ENV{NIX_CC}/nix-support/orig-libc"
-+    AND EXISTS "$ENV{NIX_CC}/nix-support/orig-libc-dev")
-+    file(STRINGS "$ENV{NIX_CC}/nix-support/orig-libc" _nix_cmake_libc)
-+    file(STRINGS "$ENV{NIX_CC}/nix-support/orig-libc-dev" _nix_cmake_libc_dev)
-+  else()
-+    set(_nix_cmake_libc @libc_lib@)
-+    set(_nix_cmake_libc_dev @libc_dev@)
-+  endif()
++if(DEFINED ENV{NIX_CC}
++  AND IS_DIRECTORY "$ENV{NIX_CC}"
++  AND EXISTS "$ENV{NIX_CC}/nix-support/orig-libc"
++  AND EXISTS "$ENV{NIX_CC}/nix-support/orig-libc-dev")
++  file(STRINGS "$ENV{NIX_CC}/nix-support/orig-libc" _nix_cmake_libc)
++  file(STRINGS "$ENV{NIX_CC}/nix-support/orig-libc-dev" _nix_cmake_libc_dev)
++else()
++  set(_nix_cmake_libc @libc_lib@)
++  set(_nix_cmake_libc_dev @libc_dev@)
 +endif()
 +
  list(APPEND CMAKE_SYSTEM_INCLUDE_PATH