Fix building on musl libc.

src/common/linux/dump_symbols.cc

Index: src/common/linux/dump_symbols.cc
diff --git a/src/common/linux/dump_symbols.cc b/src/common/linux/dump_symbols.cc
index d6c593fa3fd37bd0b4620ec96efc83ddc6d7b550..9f3f2c6f0c69082af3a85a72e9619cb302ca92dc 100644
--- a/src/common/linux/dump_symbols.cc
+++ b/src/common/linux/dump_symbols.cc
@@ -848,9 +848,9 @@ string FormatIdentifier(unsigned char identifier[16]) {
 // last slash, or the whole filename if there are no slashes.
 string BaseFileName(const string &filename) {
   // Lots of copies!  basename's behavior is less than ideal.
-  char* c_filename = strdup(filename.c_str());
-  string base = basename(c_filename);
-  free(c_filename);
+  const char *c_filename = filename.c_str();
+  const char *p = strrchr(c_filename, '/');
+  string base = p ? p+1 : c_filename;
   return base;
 }