external: update external revisions

Update external revisions for glslang, spirv-tools, spirv-headers, and
shaderc.

Change-Id: Ie1f4afe2d36a6d8e3d1e166c23372f8f6523cf59
diff --git a/build-android/glslang_revision_android b/build-android/glslang_revision_android
index 45564df..e187357 100644
--- a/build-android/glslang_revision_android
+++ b/build-android/glslang_revision_android
@@ -1 +1 @@
-1a010b8368abfbb0168490d7690697649ef3d035
+2c6f48b1f613c3161ff7052e831249be0307cbaa
diff --git a/build-android/shaderc_revision_android b/build-android/shaderc_revision_android
index b708d35..9e3bf98 100644
--- a/build-android/shaderc_revision_android
+++ b/build-android/shaderc_revision_android
@@ -1 +1 @@
-21e20163a29a15922f5b018d684b67e9e40b5298
+580d5402003be96ae1c4d59ab6a7d10f85647d92
diff --git a/build-android/spirv-headers_revision_android b/build-android/spirv-headers_revision_android
index ebb6f9f..952227b 100644
--- a/build-android/spirv-headers_revision_android
+++ b/build-android/spirv-headers_revision_android
@@ -1 +1 @@
-db5cf6176137003ca4c25df96f7c0649998c3499
+63e1062a194750b354d48be8c16750d7a4d0dc4e
diff --git a/build-android/spirv-tools_revision_android b/build-android/spirv-tools_revision_android
index d455837..95f8de0 100644
--- a/build-android/spirv-tools_revision_android
+++ b/build-android/spirv-tools_revision_android
@@ -1 +1 @@
-eb720b2ad1d80159a82ebb2b47e2ea7b911dba67
+dbc2049aa35a06b160b91fb76820358a17b77bfa
diff --git a/external_revisions/glslang_revision b/external_revisions/glslang_revision
index 45564df..e187357 100644
--- a/external_revisions/glslang_revision
+++ b/external_revisions/glslang_revision
@@ -1 +1 @@
-1a010b8368abfbb0168490d7690697649ef3d035
+2c6f48b1f613c3161ff7052e831249be0307cbaa
diff --git a/external_revisions/spirv-headers_revision b/external_revisions/spirv-headers_revision
index ebb6f9f..952227b 100644
--- a/external_revisions/spirv-headers_revision
+++ b/external_revisions/spirv-headers_revision
@@ -1 +1 @@
-db5cf6176137003ca4c25df96f7c0649998c3499
+63e1062a194750b354d48be8c16750d7a4d0dc4e
diff --git a/external_revisions/spirv-tools_revision b/external_revisions/spirv-tools_revision
index d455837..95f8de0 100644
--- a/external_revisions/spirv-tools_revision
+++ b/external_revisions/spirv-tools_revision
@@ -1 +1 @@
-eb720b2ad1d80159a82ebb2b47e2ea7b911dba67
+dbc2049aa35a06b160b91fb76820358a17b77bfa