[utils] Inline caffeinate logic into sole client.

- This eliminates the last client of `SwiftBuildSupport.check_call`, which is
   now replaced by `swift_build_support.shell.call`.

 - Part of SR-237.

utils/SwiftBuildSupport.py

@@ -18,7 +18,6 @@ except ImportError:
     import configparser as ConfigParser
 
 import os
-import platform
 import subprocess
 import sys
 
@@ -70,28 +69,6 @@ SWIFT_BUILD_ROOT = os.environ.get(
     "SWIFT_BUILD_ROOT", os.path.join(SWIFT_SOURCE_ROOT, "build"))
 
 
-def check_call(args, print_command=False, verbose=False, disable_sleep=False):
-    if disable_sleep:
-        if platform.system() == 'Darwin':
-            # Don't mutate the caller's copy of the arguments.
-            args = list(args)
-            args.insert(0, "caffeinate")
-
-    if print_command:
-        print(os.getcwd() + "$ " + shell.quote_command(args))
-        sys.stdout.flush()
-    try:
-        return subprocess.check_call(args)
-    except subprocess.CalledProcessError as e:
-        diagnostics.fatal(
-            "command terminated with a non-zero exit status " +
-            str(e.returncode) + ", aborting")
-    except OSError as e:
-        diagnostics.fatal(
-            "could not execute '" + shell.quote_command(args) +
-            "': " + e.strerror)
-
-
 def check_output(args, print_command=False, verbose=False):
     if print_command:
         print(os.getcwd() + "$ " + shell.quote_command(args))