simpleperf: show <> correctly in html report.

Html regards <> as tags, so it can't show source code and disassembly
with <> correctly. Fix this by replacing <> with '&gt;' and '&lt;'.

Also increase the percentage rectangle in FlamegraphView.

Bug: http://b/69128442
Test: run report_html.py on a perf.data having samples of a template function.
Change-Id: Ibbcfaac0cfaf56f10787ef6eea135f6ae781bd5a
2 files changed