assembler_thumb_test: use 'objdump -D -M force-thumb' to disassemble.

Newer version of objcopy cannot strip '$d' from an object file, as it is
implicitly marked as 'precious'. This is intentional, introduced in the
upstream binutils repository by this commit:
- https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=fca2a38fdb391f810e309a12d5279047d4edac34

Since stripping of '$d' was being done only so we can disassemble
the object file with 'objdump -d', switch to using 'objdump -D -M
force-thumb' to force disassembly as thumb instructions.

Bug: None
Test: m test-art-host-gtest-assembler_thumb_test
Change-Id: I815f9f3a7949bdc49d872c9b726c87b3199b66ca
diff --git a/compiler/utils/assembler_thumb_test.cc b/compiler/utils/assembler_thumb_test.cc
index e51b622..4dbe71b 100644
--- a/compiler/utils/assembler_thumb_test.cc
+++ b/compiler/utils/assembler_thumb_test.cc
@@ -126,15 +126,8 @@
   int cmd_result = system(cmd);
   ASSERT_EQ(cmd_result, 0) << strerror(errno);
 
-  // Remove the $d symbols to prevent the disassembler dumping the instructions
-  // as .word
-  snprintf(cmd, sizeof(cmd), "%sobjcopy -N '$d' %s.o %s.oo", toolsdir.c_str(), filename, filename);
-  int cmd_result2 = system(cmd);
-  ASSERT_EQ(cmd_result2, 0) << strerror(errno);
-
   // Disassemble.
-
-  snprintf(cmd, sizeof(cmd), "%sobjdump -d %s.oo | grep '^  *[0-9a-f][0-9a-f]*:'",
+  snprintf(cmd, sizeof(cmd), "%sobjdump -D -M force-thumb --section=.text %s.o  | grep '^  *[0-9a-f][0-9a-f]*:'",
     toolsdir.c_str(), filename);
   if (kPrintResults) {
     // Print the results only, don't check. This is used to generate new output for inserting
@@ -169,9 +162,6 @@
   char buf[FILENAME_MAX];
   snprintf(buf, sizeof(buf), "%s.o", filename);
   unlink(buf);
-
-  snprintf(buf, sizeof(buf), "%s.oo", filename);
-  unlink(buf);
 #endif  // ART_TARGET_ANDROID
 }