graph-build-time: generate graphs based on timing data

graph-build-time: generate graphs based on timing data

This script generates graphs of packages build time, from the timing
data generated by Buildroot in the $(O)/build-time.log file.

Example usage:

  ./support/scripts/graph-build-time \
      --type=histogram --input=$(O)/build-time.log --output=foobar.pdf

Three graph types are available :

  * histogram, which creates an histogram of the build time for each
    package, decomposed by each step (extract, patch, configure,
    etc.). The order in which the packages are shown is
    configurable: by package name, by build order, or by duration
    order. See the --order option.

  * pie-packages, which creates a pie chart of the build time of
    each package (without decomposition in steps). Packages that
    contributed to less than 1% of the overall build time are all
    grouped together in an "Other" entry.

  * pie-steps, which creates a pie chart of the time spent globally
    on each step (extract, patch, configure, etc...)

The default is to generate an histogram ordered by package name.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
[yann.morin.1998@free.fr: adapt to the format of the step-hooks build-time.log,
    add sort order by name, default to name-ordered histogram, use our colours
    for pie-charts, add alternate color-scheme, add short-options, add
    --input/-i]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>