Use thumb versions of external libraries with ARMv7.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index b8a87e09c707e3b6bc7cf47fcd41bbcdd8499e9a..4e7c83635526e54449a9dbac4774592147457b4d 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -2342,6 +2342,7 @@
       }, {
          'use_seccomp_bpf%': 0,
       }],
+
       # Set component build with LTO until all tests pass.
       # This also reduces link time.
       ['use_lto==1', {
@@ -2380,7 +2381,7 @@
     # Whether to allow building of the GPU-related isolates.
     'archive_gpu_tests%': 0,
 
-     # Whether to allow building of chromoting related isolates.
+    # Whether to allow building of chromoting related isolates.
     'archive_chromoting_tests%': 0,
   },
   'target_defaults': {
@@ -4632,10 +4633,19 @@
                   '--sysroot=<(android_ndk_sysroot)',
                   '-nostdlib',
                 ],
+                'variables': {
+                  'conditions': [
+                    ['target_arch=="arm" and arm_thumb==1', {
+                      'thumb_option%': '-mthumb',
+                    }, {
+                      'thumb_option%': '',
+                    }],
+                  ],
+                },
                 'libraries': [
                   '-l<(android_stlport_library)',
                   # Manually link the libgcc.a that the cross compiler uses.
-                  '<!(<(android_toolchain)/*-gcc -print-libgcc-file-name)',
+                  '<!(<(android_toolchain)/*-gcc <(thumb_option) -print-libgcc-file-name)',
                   '-lc',
                   '-ldl',
                   '-lm',
@@ -4700,8 +4710,12 @@
                 'cflags': [
                   '-isystem<(android_stlport_include)',
                 ],
-                'ldflags': [
-                  '-L<(android_stlport_libs_dir)',
+                'conditions': [
+                  ['target_arch=="arm" and arm_thumb==1', {
+                    'ldflags': [ '-L<(android_stlport_libs_dir)/thumb' ]
+                  }, {
+                    'ldflags': [ '-L<(android_stlport_libs_dir)' ]
+                  }],
                 ],
               }, { # else: android_webview_build!=0
                 'aosp_build_settings': {