Add a better test case for nested probe reads

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

Add support for static helper functions

This adds support for static helper functions that can be reused. It is
not necessary to include pt_regs in the helper functions, even though
external pointers may be dereferenced. Arguments in the helpers can also
be reordered.
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

add biosnoop to README

biosnoop and disk updates

Fix probe reads on char[] types

It is easy enough to wrap the type in a typeof(), otherwise the rewriter
would need to do a deeper parsing of the type information to place it
properly next to the variable name.

Fixes: #219
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Translate multiple pointer dereference into bpr_probe_read

This commit adds support for multiple consecutive and nested pointer
dereference of function arguments that should be converted to
bpf_probe_read. The logic works by marking variables as needing a
probe_read if they come from the register argument, and then applying
this property transitively.

Supported syntax:
```
int trace_entry(struct pt_regs *ctx, struct file *file) {
    struct vfsmount *mnt = file->f_path.mnt;
    struct super_block *k = mnt->mnt_sb;
    const char *name = file->f_path.dentry->d_name.name;
```

Not supported: probe reads from map leaves, probe reads after explicit casts.

Fixes: #188
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

add ebpf method to retrieve bytecode

This is useful if you want to use bcc as a compiler without running the
program.

updated  mainline version to support bridge

Change test_xlate1 to use act_bpf instead of cls_bpf

Support for act_bpf is available for testing in
https://github.com/drzaeus77/pyroute2Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Don't include git tag in .so suffix

The git hash was being include in the shared library name. This leads to
polution of the /usr/lib directory. Instead, just use the latest tag in
the library suffix.

As a developer, you will need to clean up the /usr/lib/libbcc* files
whenever a new tag is created.

Fixes: #207
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

sync readme hello_world.py example with actual implementation

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

Add clang command line invocation to debug=0x4

This adds the command line arguments of clang to debug flag 0x4 in the
clang frontend.
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

some README rework

funccount and BPF_HASH updates