[NFC][Build System: build-script] Remove the old which module in swift_build_support.

utils/scale-test

@@ -28,26 +28,20 @@ import tempfile
 from collections import namedtuple
 from operator import attrgetter
 
+from build_swift.build_swift import shell
+
 import gyb
 
 from jobstats import load_stats_dir, merge_all_jobstats
 
 
-def find_which(p):
-    for d in os.environ["PATH"].split(os.pathsep):
-        full = os.path.join(d, p)
-        if os.path.isfile(full) and os.access(full, os.X_OK):
-            return full
-    return p
-
-
 # Evidently the debug-symbol reader in dtrace is sufficiently slow and/or buggy
 # that attempting to inject probes into a binary w/ debuginfo is asking for a
 # failed run (possibly racing with probe insertion, or probing the stabs
 # entries, see rdar://problem/7037927 or rdar://problem/11490861 respectively),
 # so we sniff the presence of debug symbols here.
 def has_debuginfo(swiftc):
-    swiftc = find_which(swiftc)
+    swiftc = shell.which(swiftc)
     for line in subprocess.check_output(
             ["dwarfdump", "--file-stats", swiftc]).splitlines():
         if '%' not in line:

utils/swift_build_support/swift_build_support/__init__.py

@@ -15,8 +15,6 @@
 #
 # ----------------------------------------------------------------------------
 
-from .which import which
-
 __all__ = [
     "cmake",
     "debug",
@@ -25,6 +23,5 @@
     "tar",
     "targets",
     "toolchain",
-    "which",
     "xcrun",
 ]

utils/swift_build_support/swift_build_support/toolchain.py

@@ -18,10 +18,11 @@
 
 import platform
 
+from build_swift.build_swift.shell import which
+
 from . import cache_util
 from . import shell
 from . import xcrun
-from .which import which
 
 __all__ = [
     'host_toolchain',