map the mcontext_t structure for musl

Upstream-Status: Inappropriate [need to consider Android]

Signed-off-by: Khem Raj <raj.khem@gmail.com>
--- a/src/client/linux/minidump_writer/linux_core_dumper.cc
+++ b/src/client/linux/minidump_writer/linux_core_dumper.cc
@@ -214,7 +214,7 @@ bool LinuxCoreDumper::EnumerateThreads()
         info.tgid = status->pr_pgrp;
         info.ppid = status->pr_ppid;
 #if defined(__mips__)
-# if defined(__ANDROID__)
+# if defined(__ANDROID__) || !defined(__GLIBC__)
         for (int i = EF_R0; i <= EF_R31; i++)
           info.mcontext.gregs[i - EF_R0] = status->pr_reg[i];
 # else  // __ANDROID__
