Patch to ensure e_machine is properly initialized in some cases where
we attach to a running multi-threaded process.

diff -rup a/proc.c b/proc.c
--- a/proc.c	2019-02-28 17:32:50.020734842 -0500
+++ b/proc.c	2019-02-28 21:04:31.179942091 -0500
@@ -38,6 +38,7 @@
 #include "breakpoint.h"
 #include "debug.h"
 #include "fetch.h"
+#include "ltrace-elf.h"
 #include "options.h"
 #include "proc.h"
 #include "value_dict.h"
@@ -218,6 +219,21 @@ process_init(struct process *proc, const
 		return -1;
 	}
 
+	{
+	       struct ltelf lte;
+
+	       if (ltelf_init(&lte, filename) < 0) {
+		       process_bare_destroy(proc, 0);
+		       goto fail;
+	       }
+
+	       proc->e_machine = lte.ehdr.e_machine;
+	       proc->e_class = lte.ehdr.e_ident[EI_CLASS];
+	       get_arch_dep(proc);
+
+	       ltelf_destroy(&lte);
+       }
+
 	if (os_process_init(proc) < 0) {
 		process_bare_destroy(proc, 0);
 		goto fail;
diff -rup a/sysdeps/linux-gnu/x86/fetch.c b/sysdeps/linux-gnu/x86/fetch.c
--- a/sysdeps/linux-gnu/x86/fetch.c	2019-02-28 17:32:50.168810377 -0500
+++ b/sysdeps/linux-gnu/x86/fetch.c	2019-02-28 20:57:32.162800555 -0500
@@ -275,6 +275,9 @@ allocate_integer(struct fetch_context *c
 #undef HANDLE32
 		}
 
+		assert(!"Unknown machine architecture");
+		abort();
+
 	case POOL_RETVAL:
 		switch (context->ireg) {
 #ifdef __x86_64__