Mark vertex_texcoords_available() as const

9 jobs from const-correct-texcoord in 3 minutes and 52 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #38612
VS2013
VS2013-32-bit

00:00:56

passed #38611
VS2013
VS2013-64-bit

00:00:55

passed #38610
VS2015
VS2015-32-bit

00:01:00

passed #38609
VS2015
VS2015-64-bit

00:01:19

passed #38606
Linux
clang-c++11

00:03:36

passed #38608
Linux
cppcheck

00:00:47

passed #38613
Linux
doc

00:00:21

passed #38605
Linux
gcc-c++11

00:03:52

passed #38607
Apple
macos-c++11

00:01:28