[libc++][Android] XFAIL aligned_alloc and timespec_get tests

Mark tests XFAIL that use APIs that are unsupported on old versions of
Android:
 - aligned_alloc isn't available until API 28.
 - timespec_get isn't available until API 29.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D137134

Author: rprichard

libcxx/test/std/depr/depr.c.headers/stdlib_h.aligned_alloc.compile.pass.cpp

@@ -18,6 +18,9 @@
 // ::aligned_alloc is not implemented on Windows
 // XFAIL: target={{.+}}-windows-{{.+}}
 
+// ::aligned_alloc is available starting with Android P (API 28)
+// XFAIL: target={{.+}}-android{{(eabi)?(21|22|23|24|25|26|27)}}
+
 #include <stdlib.h>
 #include <type_traits>
 

libcxx/test/std/language.support/support.runtime/cstdlib.aligned_alloc.compile.pass.cpp

@@ -18,6 +18,9 @@
 // ::aligned_alloc is not implemented on Windows
 // XFAIL: target={{.+}}-windows-{{.+}}
 
+// ::aligned_alloc is available starting with Android P (API 28)
+// XFAIL: target={{.+}}-android{{(eabi)?(21|22|23|24|25|26|27)}}
+
 #include <cstdlib>
 #include <type_traits>
 

libcxx/test/std/language.support/support.runtime/ctime.timespec.compile.pass.cpp

@@ -17,6 +17,9 @@
 // unavailable until macOS 10.15
 // XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14}}
 
+// ::timespec_get is available starting with Android Q (API 29)
+// XFAIL: target={{.+}}-android{{(eabi)?(21|22|23|24|25|26|27|28)}}
+
 #include <ctime>
 #include <type_traits>