Removed syntastic and replaced it with ale

Read more here:
https://github.com/w0rp/ale

sources_non_forked/ale/ale_linters/cpp/gcc.vim

@@ -0,0 +1,32 @@
+" Author: geam <mdelage@student.42.fr>
+" Description: gcc linter for cpp files
+"
+call ale#Set('cpp_gcc_executable', 'gcc')
+call ale#Set('cpp_gcc_options', '-std=c++14 -Wall')
+
+function! ale_linters#cpp#gcc#GetExecutable(buffer) abort
+    return ale#Var(a:buffer, 'cpp_gcc_executable')
+endfunction
+
+function! ale_linters#cpp#gcc#GetCommand(buffer, output) abort
+    let l:cflags = ale#c#GetCFlags(a:buffer, a:output)
+
+    " -iquote with the directory the file is in makes #include work for
+    "  headers in the same directory.
+    return ale#Escape(ale_linters#cpp#gcc#GetExecutable(a:buffer))
+    \   . ' -S -x c++ -fsyntax-only '
+    \   . '-iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h')) . ' '
+    \   . l:cflags
+    \   . ale#Var(a:buffer, 'cpp_gcc_options') . ' -'
+endfunction
+
+call ale#linter#Define('cpp', {
+\   'name': 'g++',
+\   'output_stream': 'stderr',
+\   'executable_callback': 'ale_linters#cpp#gcc#GetExecutable',
+\   'command_chain': [
+\       {'callback': 'ale#c#GetMakeCommand', 'output_stream': 'stdout'},
+\       {'callback': 'ale_linters#cpp#gcc#GetCommand'},
+\   ],
+\   'callback': 'ale#handlers#gcc#HandleGCCFormat',
+\})