build(lint): fix luacheck not found #18940

Problem:
Since 6d57bb89c1ee #18543, luacheck is not found on some systems when
running the "lintlua" target.

Solution:
- Move the find_program() to the top-level CMakeLists.txt
- Define a def_cmd_target() function with fewer assumptions than the old
  lint() function.
- Move "lintuncrustify" to src/nvim/CMakeLists.txt so it can reuse the
  $LINT_NVIM_SOURCES already defined there.
- Make the lint targets _fatal_ by default. There is little reason for
  the "lint" umbrella target defined in Makefile to exist if it's going
  to ignore the absence of the actual linters.
- For now, keep the uncrustify call in a separate cmake script so that
  it can be silenced (too noisy).

1 files changed, 5 insertions, 0 deletions

diff --git a/cmake/RunUncrustify.cmake b/cmake/RunUncrustify.cmake
new file mode 100644
index 0000000000..9ebbd6b77c
--- /dev/null
+++ b/cmake/RunUncrustify.cmake
@@ -0,0 +1,5 @@
+# HACK: This script is invoked with "cmake -P …" as a workaround to silence uncrustify.
+
+execute_process(
+  COMMAND ${UNCRUSTIFY_PRG} -c "${PROJECT_SOURCE_DIR}/src/uncrustify.cfg" -q --check ${LINT_NVIM_SOURCES}
+  OUTPUT_QUIET)