cmake/LuaHelpers.cmake: check_lua_module: display errors

This helps to figure out what the problem is, e.g. in my case I have
lua51-mpack installed to be used with luajit, but it is broken (missing
libmpack).

With this patch you get:

    -- Checking Lua interpreter /usr/bin/luajit
    /usr/bin/luajit: error loading module 'mpack' from file '/usr/lib/lua/5.1/mpack.so':
            libmpack.so.0: cannot open shared object file: No such file or directory
    stack traceback:
            [C]: at 0x55fcf0166fb0
            [C]: in function 'require'
            (command line):1: in main chunk
            [C]: at 0x55fcf01188a0
    -- [/usr/bin/luajit] The 'mpack' lua package is required for building Neovim
    -- Checking Lua interpreter /usr/bin/lua5.1
    /usr/bin/lua5.1: error loading module 'mpack' from file '/usr/lib/lua/5.1/mpack.so':
            libmpack.so.0: cannot open shared object file: No such file or directory
    stack traceback:
            [C]: ?
            [C]: in function 'require'
            (command line):1: in main chunk
            [C]: ?
    -- [/usr/bin/lua5.1] The 'mpack' lua package is required for building Neovim
    -- Checking Lua interpreter /usr/bin/lua5.2
    /usr/bin/lua5.2: (command line):1: module 'mpack' not found:
            no field package.preload['mpack']
            no file '/usr/share/lua/5.2/mpack.lua'
            no file '/usr/share/lua/5.2/mpack/init.lua'
            no file '/usr/lib/lua/5.2/mpack.lua'
            no file '/usr/lib/lua/5.2/mpack/init.lua'
            no file './mpack.lua'
            no file '/usr/lib/lua/5.2/mpack.so'
            no file '/usr/lib/lua/5.2/loadall.so'
            no file './mpack.so'
    stack traceback:
            [C]: in function 'require'
            (command line):1: in main chunk
            [C]: in ?
    -- [/usr/bin/lua5.2] The 'mpack' lua package is required for building Neovim
    -- Checking Lua interpreter /usr/bin/lua
    /usr/bin/lua: (command line):1: module 'mpack' not found:
            no field package.preload['mpack']
            no file '/usr/share/lua/5.3/mpack.lua'
            no file '/usr/share/lua/5.3/mpack/init.lua'
            no file '/usr/lib/lua/5.3/mpack.lua'
            no file '/usr/lib/lua/5.3/mpack/init.lua'
            no file './mpack.lua'
            no file './mpack/init.lua'
            no file '/usr/lib/lua/5.3/mpack.so'
            no file '/usr/lib/lua/5.3/loadall.so'
            no file './mpack.so'
    stack traceback:
            [C]: in function 'require'
            (command line):1: in main chunk
            [C]: in ?
    -- [/usr/bin/lua] The 'mpack' lua package is required for building Neovim
    CMake Error at CMakeLists.txt:459 (message):
      A suitable Lua interpreter was not found.

While this makes it more verbose for the expected error case ("module
'mpack' not found"), the behavior before this patch hides too much.
This is the old output:

    -- Checking Lua interpreter /usr/bin/luajit
    -- [/usr/bin/luajit] The 'mpack' lua package is required for building Neovim
    -- Checking Lua interpreter /usr/bin/lua5.1
    -- [/usr/bin/lua5.1] The 'mpack' lua package is required for building Neovim
    -- Checking Lua interpreter /usr/bin/lua5.2
    -- [/usr/bin/lua5.2] The 'mpack' lua package is required for building Neovim
    -- Checking Lua interpreter /usr/bin/lua
    -- [/usr/bin/lua] The 'mpack' lua package is required for building Neovim
    CMake Error at CMakeLists.txt:459 (message):
      A suitable Lua interpreter was not found.

This is for when the whole configuration runs (i.e. after `make
distclean`), afterwards only one Lua interpreter gets checked only.

1 files changed, 1 insertions, 2 deletions

diff --git a/cmake/LuaHelpers.cmake b/cmake/LuaHelpers.cmake
index 32f7e46a57..a401ff75df 100644
--- a/cmake/LuaHelpers.cmake
+++ b/cmake/LuaHelpers.cmake
@@ -5,8 +5,7 @@
 # Check if a module is available in Lua
 function(check_lua_module LUA_PRG_PATH MODULE RESULT_VAR)
   execute_process(COMMAND ${LUA_PRG_PATH} -e "require('${MODULE}')"
-    RESULT_VARIABLE module_missing
-    ERROR_QUIET)
+    RESULT_VARIABLE module_missing)
   if(module_missing)
     set(${RESULT_VAR} False PARENT_SCOPE)
   else()