PR #2087: Consistently use __APPLE__ to identify macOS OSes

Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/2087

`__MACH__` may identify also other OSes based on some Mach variation.
Merge 9b56ad7f05f24da3a16502704aa760d614a2073b into ad568ab75f7464eb232855bd0f0a625aa1b784f0

Merging this change closes #2087

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/2087 from pinotree:test-apple-define 9b56ad7f05f24da3a16502704aa760d614a2073b
PiperOrigin-RevId: 936948219
Change-Id: I0bac1bdd0fbba102b26134ddab8b2a87d4689d72

absl/log/stripping_test.cc

diff --git a/absl/log/stripping_test.cc b/absl/log/stripping_test.cc
index 271fae1..20231b9 100644
--- a/absl/log/stripping_test.cc
+++ b/absl/log/stripping_test.cc
@@ -33,7 +33,7 @@
 
 #include <stdio.h>
 
-#if defined(__MACH__)
+#if defined(__APPLE__)
 #include <mach-o/dyld.h>
 #elif defined(_WIN32)
 #include <Windows.h>
@@ -191,7 +191,7 @@
       absl::FPrintF(stderr, "Failed to open /pkg/bin/<binary name>: %s\n", err);
     }
     return fp;
-#elif defined(__MACH__)
+#elif defined(__APPLE__)
     uint32_t size = 0;
     int ret = _NSGetExecutablePath(nullptr, &size);
     if (ret != -1) {