[REVIEW][3-5] fdo#38215: sw: fix consecutive border line gaps regression

[Michael Stahl]

this fixes a regression in painting border lines in LO 3.4, leading to
small visible gaps between borders of consecutive paragraphs, and is
proposed for libreoffice-3-5.

fixed by re-implementing the merging of border lines that are less than
1.5 pixel apart that was done in the old paint implementation.

http://cgit.freedesktop.org/libreoffice/core/commit/?id=0868a0155a2b57daf7b862d120aead0458372b17

the fix first requires this commit because "start" being the smaller Y
coordinate but the larger X coordinate was very confusing:

http://cgit.freedesktop.org/libreoffice/core/commit/?id=1d5e263a129c56e561ce145bad9749027c583a75

also this one because apparently my gcc is unusually un-idiotic:

http://cgit.freedesktop.org/libreoffice/core/commit/?id=44092833d3a0f0d6074c64bd0e64bbdf11109afe