configure: use pkgconfig to detect samba

Recent Samba versions require pkg-config. We try that first but fall
back to old behaviour if smbclient.pc is missing.

This solves also an 'issue' with samba4 that correctly detects the
libsmbclient in the link test in configure, but fails to compile later
due to missing headers.

Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
[WIN32] fixed: python package name was wrong
Merge pull request #3537 from wsnipex/samba4

configure: use pkgconfig to detect samba
[win32] properly check status of formed packages
[win32] explicitly set zero exit code on success
Merge pull request #3539 from Karlson2k/win32_check_packages

Win32: check packages
[rbp/omxplayer] Avoid clipping with amplification

The amplification algorithm introduced in #3185 relies on a fixed duration between
submitting samples (where max output values are computed) and samples being output,
so volume can be adjusted in time.

When this is too low, such as at start of stream when buffering is low we can apply
attenuation too late and so produce a loud distorted/clipped sound.

When too high, the attenuation can start to decay before the max sample is output,
again causing clipping.

This PR keeps a queue of max sample values for the current buffered audio duration,
and avoids clipping if any sample in queue will clip.