#5469 Add `TEX` environemnt variable for texi2pdf

[Masamichi Hosoda]

Add TEX environemnt variable for texi2pdf

Even if using texi2pdf
with PDFTEX=xetex-with-options environment variable,
texi2pdf invokes etex instead of xetex-with-options
for requiring texinfo.tex version.

Therefore, texi2pdf failed in environments
where invoking etex failes like a GUB environment
on some OS which contain newer libc.

This commit adds TEX environment variable
with the same contents as the PDFTEX environment variable
when invoking texi2pdf.

If using texi2pdf with TEX=xetex-with-options environment variable,
texi2pdf invokes xetex-with-options for requiring texinfo.tex version
and it succeeds on the environments where etex fails.

Tweak wrapped lines

http://codereview.appspot.com/353870043

[Anonymous]

Passes make, make check and a full make doc.

[Anonymous]

Patch on countdown for Feb 4th.

[Anonymous]

Patch counted down - please push.

[Masamichi Hosoda]

I've pushed to staging.

commit 88633ac5cf54db38a07ebacc16e38dcabad6f843
Issue 5469/2: Add TEX environemnt variable for texi2pdf

commit e757c642cb86f37ad3d069c9c6eff54360486045
Issue 5469/1: Tweak wrapped lines