uu: Replace return_if_err with crash_if_err

Unify the usage of macros `return_if_err` and `crash_if_err`. As
`return_if_err` is used only in `uumain` routines of utilities, it
achieves the same thing as `crash_if_err`, which calls the `crash!`
macro to terminate function execution immediately.

src/uu/csplit/src/csplit.rs

@@ -725,14 +725,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .unwrap()
         .map(str::to_string)
         .collect();
-    let patterns = return_if_err!(1, patterns::get_patterns(&patterns[..]));
+    let patterns = crash_if_err!(1, patterns::get_patterns(&patterns[..]));
     let options = CsplitOptions::new(&matches);
     if file_name == "-" {
         let stdin = io::stdin();
         crash_if_err!(1, csplit(&options, patterns, stdin.lock()));
     } else {
-        let file = return_if_err!(1, File::open(file_name));
+        let file = crash_if_err!(1, File::open(file_name));
-        let file_metadata = return_if_err!(1, file.metadata());
+        let file_metadata = crash_if_err!(1, file.metadata());
         if !file_metadata.is_file() {
             crash!(1, "'{}' is not a regular file", file_name);
         }

src/uu/seq/src/seq.rs

@@ -105,7 +105,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         let dec = slice.find('.').unwrap_or(len);
         largest_dec = len - dec;
         padding = dec;
-        return_if_err!(1, slice.parse())
+        crash_if_err!(1, slice.parse())
     } else {
         Number::BigInt(BigInt::one())
     };
@@ -115,7 +115,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         let dec = slice.find('.').unwrap_or(len);
         largest_dec = cmp::max(largest_dec, len - dec);
         padding = cmp::max(padding, dec);
-        return_if_err!(1, slice.parse())
+        crash_if_err!(1, slice.parse())
     } else {
         Number::BigInt(BigInt::one())
     };
@@ -130,7 +130,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let last = {
         let slice = numbers[numbers.len() - 1];
         padding = cmp::max(padding, slice.find('.').unwrap_or_else(|| slice.len()));
-        return_if_err!(1, slice.parse())
+        crash_if_err!(1, slice.parse())
     };
     if largest_dec > 0 {
         largest_dec -= 1;

src/uu/stdbuf/src/stdbuf.rs

@@ -170,7 +170,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let command_params: Vec<&str> = command_values.collect();
 
     let mut tmp_dir = tempdir().unwrap();
-    let (preload_env, libstdbuf) = return_if_err!(1, get_preload_env(&mut tmp_dir));
+    let (preload_env, libstdbuf) = crash_if_err!(1, get_preload_env(&mut tmp_dir));
     command.env(preload_env, libstdbuf);
     set_command_env(&mut command, "_STDBUF_I", options.stdin);
     set_command_env(&mut command, "_STDBUF_O", options.stdout);

src/uu/timeout/src/timeout.rs

@@ -221,7 +221,7 @@ fn timeout(
                     cmd[0]
                 );
             }
-            return_if_err!(ERR_EXIT_STATUS, process.send_signal(signal));
+            crash_if_err!(ERR_EXIT_STATUS, process.send_signal(signal));
             if let Some(kill_after) = kill_after {
                 match process.wait_or_timeout(kill_after) {
                     Ok(Some(status)) => {
@@ -235,13 +235,13 @@ fn timeout(
                         if verbose {
                             show_error!("sending signal KILL to command '{}'", cmd[0]);
                         }
-                        return_if_err!(
+                        crash_if_err!(
                             ERR_EXIT_STATUS,
                             process.send_signal(
                                 uucore::signals::signal_by_name_or_value("KILL").unwrap()
                             )
                         );
-                        return_if_err!(ERR_EXIT_STATUS, process.wait());
+                        crash_if_err!(ERR_EXIT_STATUS, process.wait());
                         137
                     }
                     Err(_) => 124,
@@ -251,7 +251,7 @@ fn timeout(
             }
         }
         Err(_) => {
-            return_if_err!(ERR_EXIT_STATUS, process.send_signal(signal));
+            crash_if_err!(ERR_EXIT_STATUS, process.send_signal(signal));
             ERR_EXIT_STATUS
         }
     }

src/uu/uname/src/uname.rs

@@ -53,7 +53,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let usage = format!("{} [OPTION]...", uucore::execution_phrase());
     let matches = uu_app().usage(&usage[..]).get_matches_from(args);
 
-    let uname = return_if_err!(1, PlatformInfo::new());
+    let uname = crash_if_err!(1, PlatformInfo::new());
     let mut output = String::new();
 
     let all = matches.is_present(options::ALL);