workaround ICU not supporting git yet

[srl295]

Fixes: #7

I verified that this is able to create a near-identical icu4c 62.1 package. Differences are:

• .gitignore was moved to the top level
• the bomlist file has contents in a different order (due to svn)

with this PR, make dist produces:

icu-r4a3ba8e-x86_64-pc-linux-gnu-Ubuntu-18.04-sdoc.tgz
icu-r4a3ba8e-x86_64-pc-linux-gnu-Ubuntu-18.04-src.d/icu4c-data-62_1-r4a3ba8e.zip
icu-r4a3ba8e-x86_64-pc-linux-gnu-Ubuntu-18.04-src.d/icu4c-docs-62_1-r4a3ba8e.zip
icu-r4a3ba8e-x86_64-pc-linux-gnu-Ubuntu-18.04-src.d/icu4c-src-62_1-r4a3ba8e.tgz
icu-r4a3ba8e-x86_64-pc-linux-gnu-Ubuntu-18.04-src.d/icu4c-src-62_1-r4a3ba8e.zip
icu-r4a3ba8eee9-x86_64-pc-linux-gnu-Fedora-28.tgz
icu-r4a3ba8eee9-x86_64-pc-linux-gnu-Fedora-28.tgz.md5
icu-r4a3ba8eee9-x86_64-pc-linux-gnu-Ubuntu-18.04.tgz
icu-r4a3ba8eee9-x86_64-pc-linux-gnu-Ubuntu-18.04.tgz.md5

… where the git hash unicode-org/icu@4a3ba8e refers to the tag https://github.com/unicode-org/icu/releases/tag/release-62-1

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[srl295]

@roubert is this superseded by #9 and #10 ?

[roubert]

@roubert is this superseded by #9 and #10 ?

The change to Makefile is now obsolete but the other changes replacing svnversion are still relevant.