iperf: bump to 2.0.12

iperf: bump to 2.0.12

2.0.12 change set (as of June 25th 2018)

o Change the unicast TTL default value from 1 to the system default (to be compatable with previous versions.) Mulitcast still defaults to 1.
o adpative formatting bug fix: crash occurs when values exceed 1 Tera. Add support for Tera and Peta and eliminate the potential crash condition
o configure default compile to include isochronous support (use configure --disable-isochronous to remove support)
o replace 2.0.11's --vary-load option with a more general -b option to include <mean>,<stdev>, e.g. -b 100m,40m, which will pull from a log normal distribution every 0.1 seconds
o fixes for windows cross compile (using mingw32)
o compile flags of -fPIE for android
o configure --enable-checkprograms to compile ancillary binaries used to test things such as delay, isoch, pdf generation
o compile tests when trying to use 64b seq numbers on a 32b platform
o Fix GCC ver 8 warnings

2.0.11 change set (as of May 24th, 2018)

o support for -b on server (read rate limiting)
o honor -T (ttl) for unicast. (Note: the default value is 1 so this will impact unicast tests that require routing)
o support for --isochronous traffic with optional frames per second, mean and variance uses a log normal distribution (requires configure w/-enable-isochronous and compile)
o support for --udp triggers (requires configure w/ --enable-udptriggers, early code with very limited support)
o support for --udp-histogram with optional bin width and number of bins (default is 1 millisecond bin width and 1000 bins)
o support for frame (burst) latency histograms when --isochronous is set
o support for --tx-sync with -P for synchonrized writes. Initial use is for WiFi OFDMA latency testing.
o support for --incr-dstip with -P for simultaneous flows to multiple destinations (use case is for OFDMA)
o support for --vary-load with optional weight, uses log normal distribution (requires -b to set the mean)
o support for --l2checks to detect L2 length errors not detected by v4 or v6 payload length errors (requires linux, berkeley packet filters BPFs and AF_PACKET socket support)
o support for server joining mulitcast source specific multicast (S,G) and (*,G) for both v4 and v6 on platforms that support it
o improved write counters (requires -e)
o accounting bug fix on client when write fails, this bug was introduced in 2.0.10
o slight restructure client/server traffic thread code for maintainability
o python: flow example script updates
o python: ssh node object using asyncio
o python: histograms in flows with plotting (assumed gnuplot available)
o python: hierarchical clustering of latency histograms (early code)
o man pages updates
o Note: latency histograms require client and server system clock synchronization. A GPS disciplined oscillator using Precision Time Protocol works well for this.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>