st/mesa: Increase GL_POINT_SIZE_RANGE minimum to 1.0

st/mesa: Increase GL_POINT_SIZE_RANGE minimum to 1.0

Table 23.54 of the OpenGL 4.5 spec lists the minimum values for
GL_POINT_SIZE_RANGE as [1, 1].  So zero is not allowed (even though
arguably this could be useful for MSAA rendering, where a sub-1px
point might cover only some samples...)

This fixes the WebGL 2.0 conformance suite's state.gl-get-calls test
on Chromium on Linux, which uses desktop OpenGL.  The test checks that
the minimum value of GL_ALIASED_POINT_SIZE_RANGE is 1.  Unfortunately,
that query doesn't exist in desktop GL, so it checks POINT_SIZE_RANGE,
which is the anti-aliased value.  There's not really anything better
for Chromium to do here, unfortunately.  When running Chromium with
--api=es3, it maps it to the correct query and the test already works.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>