repl: fix ctrl+z job to background on linux (#6417)

vlib/readline/readline_linux.c.v

@@ -7,9 +7,11 @@
 module readline
 
 import term
+import os
 
 #include <termios.h>
 #include <sys/ioctl.h>
+
 // Defines actions to execute
 enum Action {
 	eof
@@ -35,9 +37,12 @@ fn C.tcgetattr() int
 
 fn C.tcsetattr() int
 
-// fn C.ioctl() int
 fn C.raise()
 
+fn C.kill(int, int) int
+
+fn C.getppid() int
+
 // Enable the raw mode of the terminal
 // In raw mode all keypresses are directly sent to the program and no interpretation is done
 // Catches the SIGUSER (CTRL+C) Signal
@@ -480,6 +485,18 @@ fn (mut r Readline) history_next() {
 }
 
 fn (mut r Readline) suspend() {
+	is_standalone := os.getenv('VCHILD') != 'true'
+
+	r.disable_raw_mode()
+	if !is_standalone {
+		// We have to SIGSTOP the parent v process
+		ppid := C.getppid()
+		C.kill(ppid, C.SIGSTOP)
+	}
 	C.raise(C.SIGSTOP)
+	r.enable_raw_mode()
+	r.refresh_line()
+	if r.is_tty {
 		r.refresh_line()
 	}
+}

vlib/v/util/util.v

@@ -111,6 +111,7 @@ pub fn set_vroot_folder(vroot_path string) {
 	// can return it later to whoever needs it:
 	vname := if os.user_os() == 'windows' { 'v.exe' } else { 'v' }
 	os.setenv('VEXE', os.real_path(os.join_path(vroot_path, vname)), true)
+	os.setenv('VCHILD', 'true', true)
 }
 
 pub fn resolve_vroot(str, dir string) ?string {