Support building on Alpine Linux musl

- fix issue with NULL_BACKTRACE support (there was a typo)
- support building without libexecinfo (Alpine doesn't have it)
- support linux-musl OSTYPE

aws/utils/backtrace/bsd_backtrace.cc

@@ -15,10 +15,10 @@
 
 #include "backtrace.h"
 #include <aws/utils/writer_methods.h>
-#include <execinfo.h>
 #include <unistd.h>
 
 #ifdef BSD_BACKTRACE
+#include <execinfo.h>
 namespace aws {
 namespace utils {
 namespace backtrace {

aws/utils/backtrace/gcc_backtrace.cc

@@ -15,15 +15,14 @@
 
 #include "backtrace.h"
 #include <aws/utils/writer_methods.h>
-#include <execinfo.h>
 #include <unistd.h>
 #include <aws/utils/logging.h>
 #include <aws/utils/writer_methods.h>
 #include <cstring>
 #include <cstdio>
 
 #ifdef LIB_BACKTRACE
-
+#include <execinfo.h>
 #include <backtrace.h>
 
 namespace {

aws/utils/backtrace/null_backtrace.cc

@@ -15,10 +15,10 @@
 
 #include "backtrace.h"
 #include <aws/utils/writer_methods.h>
-#include <execinfo.h>
 #include <unistd.h>
 
-#ifdef NULL_STACKTRACE
+#ifdef NULL_BACKTRACE
+#include <execinfo.h>
 
 namespace aws {
 namespace utils {
@@ -36,4 +36,4 @@ void stack_trace_for_signal(int skip, bool /*signaled*/) {
 }
 }
 
-#endif // NULL_STACKTRACE
+#endif // NULL_BACKTRACE

aws/utils/signal_handler.cc

@@ -19,7 +19,6 @@
 #include "backtrace/backtrace.h"
 
 #include <signal.h>
-#include <execinfo.h>
 #include <unistd.h>
 #include <cstring>
 #include <cstdint>

bootstrap.sh

@@ -40,6 +40,9 @@ function find_release_type() {
   if [[ $OSTYPE == "linux-gnu" ]]; then
     echo "linux-$(uname -m)"
     return
+  elif [[ $OSTYPE == "linux-musl" ]]; then
+    echo "linux-musl-$(uname -m)"
+    return
   elif [[ $OSTYPE == darwin* ]]; then
     echo "osx"
     return