Tentatively align on all platforms in embedded builtins

We've recently run into several platform- and compiler-specific errors
and warnings about alignment. This tentatively implements
AlignToDataAlignment for all platforms, which is used when setting up
the

 v8_Default_embedded_blob_
 v8_Default_embedded_blob_size_

variables.

Bug: v8:6666,chromium:929205
Change-Id: I0cee09eda71551f8b7d14f4076da496057023146
Reviewed-on: https://chromium-review.googlesource.com/c/1458018
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59428}

src/snapshot/embedded-file-writer.cc

@@ -175,7 +175,9 @@ void PlatformDependentEmbeddedFileWriter::AlignToCodeAlignment() {
   fprintf(fp_, ".balign 32\n");
 }
 
-void PlatformDependentEmbeddedFileWriter::AlignToDataAlignment() {}
+void PlatformDependentEmbeddedFileWriter::AlignToDataAlignment() {
+  fprintf(fp_, ".balign 8\n");
+}
 
 void PlatformDependentEmbeddedFileWriter::Comment(const char* string) {
   fprintf(fp_, "// %s\n", string);
@@ -262,7 +264,9 @@ void PlatformDependentEmbeddedFileWriter::AlignToCodeAlignment() {
   fprintf(fp_, ".align 5\n");
 }
 
-void PlatformDependentEmbeddedFileWriter::AlignToDataAlignment() {}
+void PlatformDependentEmbeddedFileWriter::AlignToDataAlignment() {
+  fprintf(fp_, ".align 3\n");
+}
 
 void PlatformDependentEmbeddedFileWriter::Comment(const char* string) {
   fprintf(fp_, "// %s\n", string);
@@ -354,7 +358,9 @@ void PlatformDependentEmbeddedFileWriter::AlignToCodeAlignment() {
   fprintf(fp_, "ALIGN 4\n");
 }
 
-void PlatformDependentEmbeddedFileWriter::AlignToDataAlignment() {}
+void PlatformDependentEmbeddedFileWriter::AlignToDataAlignment() {
+  fprintf(fp_, "ALIGN 4\n");
+}
 
 void PlatformDependentEmbeddedFileWriter::Comment(const char* string) {
   fprintf(fp_, "; %s\n", string);