expand response file for subtool commands

[moritzx22]

Related PRs

#1760 #2698

Problem description and current master branch

Ninja does not expand response files in the subtool commands.

# build.ninja
rule cc
  command = gcc @${out}.rsp -o ${out}
  rspfile = ${out}.rsp
  rspfile_content = -Iinclude -O2 $in

build myprog: cc file1.c file2.c file3.c

$ninja -t commands
gcc @myprog.rsp -o myprog

Proposed Solution

$ninja -t commands -x
gcc -Iinclude -O2 file1.c file2.c file3.c -o myprog

option or default

#1760 (comment)
This can be done as the default without a flag, but to be consistent with compdb I used the flag -x