Do not build breakpad tool on target when cross-compiling for iOS

The "microdump_stackwalk", "minidump_stackwalk", and "minidump_dump" tools
are not expected to be run on the device, so only build them for "host"
toolset not "target" when targetting iOS.

When building for other targets build the tools both for "host" and "target"
to fix compilation of ChromeOS build in `cros chrome-sdk` shells.

BUG=459035
TBR=mark

Review URL: https://codereview.chromium.org/938763004

Cr-Commit-Position: refs/heads/master@{#316879}

breakpad/breakpad.gyp

@@ -17,7 +17,6 @@
           # GN version: //breakpad:stackwalk_common
           'target_name': 'stackwalk_common',
           'type': 'static_library',
-          'toolsets': ['host'],
           'includes': ['breakpad_tools.gypi'],
           'defines': ['BPLOG_MINIMUM_SEVERITY=SEVERITY_ERROR'],
           'sources': [
@@ -92,12 +91,16 @@
             'src/third_party/libdisasm/x86_operand_list.c',
             'src/third_party/libdisasm/x86_operand_list.h',
           ],
+          'conditions': [
+            ['OS=="ios"', {
+              'toolsets': ['host'],
+            }],
+          ],
         },
         {
           # GN version: //breakpad:microdump_stackwalk
           'target_name': 'microdump_stackwalk',
           'type': 'executable',
-          'toolsets': ['host'],
           'dependencies': ['stackwalk_common'],
           'includes': ['breakpad_tools.gypi'],
           'defines': ['BPLOG_MINIMUM_SEVERITY=SEVERITY_ERROR'],
@@ -106,12 +109,16 @@
             'src/processor/microdump_processor.cc',
             'src/processor/microdump_stackwalk.cc',
           ],
+          'conditions': [
+            ['OS=="ios"', {
+              'toolsets': ['host'],
+            }],
+          ],
         },
         {
           # GN version: //breakpad:minidump_stackwalk
           'target_name': 'minidump_stackwalk',
           'type': 'executable',
-          'toolsets': ['host'],
           'dependencies': ['stackwalk_common'],
           'includes': ['breakpad_tools.gypi'],
           'defines': ['BPLOG_MINIMUM_SEVERITY=SEVERITY_ERROR'],
@@ -125,12 +132,16 @@
             'src/processor/minidump_processor.cc',
             'src/processor/minidump_stackwalk.cc',
           ],
+          'conditions': [
+            ['OS=="ios"', {
+              'toolsets': ['host'],
+            }],
+          ],
         },
         {
           # GN version: //breakpad:minidump_dump
           'target_name': 'minidump_dump',
           'type': 'executable',
-          'toolsets': ['host'],
           'includes': ['breakpad_tools.gypi'],
           'sources': [
             'src/processor/basic_code_module.h',
@@ -145,6 +156,11 @@
             'src/processor/pathname_stripper.cc',
             'src/processor/pathname_stripper.h',
           ],
+          'conditions': [
+            ['OS=="ios"', {
+              'toolsets': ['host'],
+            }],
+          ],
         },
       ],
     }],