Update rpm build scripts and README

Print traceback only if verbose mode was requested

trace: trace function execution with custom format strings and filters

Remove the unused Dockerfiles.

Create two flavors of spec files, one which includes steps to build
clang from source and link against it, and one which assumes clang is
already available and just builds bcc. The former is more appropriate
for official packaging, the latter for nightly and quick builds.

Also, introduce a numbering scheme for nightly rpm files. The format
will be:
`libbcc-$latest_git_tag-g$latest_git_hash.x86_64.rpm`
as in:
`libbcc-0.1.7-g73c4d1a.x86_64.rpm`

Update the INSTALL.md to mention the RPMs
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Documentation and tcp4connect enhancements

tcpconnlat

Migrated killsnoop to bpf_perf_event

syncsnoop migrated to use bpf_perf_events

Migrated filelife to bpf_perf_event

http_filter readme fixed

migration of statsnoop to use bpf_perf_event

Fix syntax error in bpf_get_prandom_u32

Fixes: #398
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Embed runtime header files in libbcc.so

To avoid installing header files needed by clang to disk
(/usr/share/bcc), embed the files as strings inside the library and feed
them to clang as memory buffers. The mechanism that we use to do this
retains all of the existing features, as in one can still do `#include
<bcc/helpers.h>`, even though it is redundant, and clang will pick up
the embedded file.

Fixes: #333
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>