glsl: Don't convert reductions of ivec to a dot-product

glsl: Don't convert reductions of ivec to a dot-product

Mesa has an optimization that converts expressions like "v.x + v.y + v.z
+ v.w" into dot(v, 1.0).  And therein lies the rub: the other operand to
the dot-product is always a float... even if the vector is an ivec or
uvec.  This results in an assertion failure in ir_builder.

If the base type of the operand is not float, don't try the
optimization.  Dot-product is not valid on integer data.

Fixes piglit vs-integer-reduction.shader_test and OpenGL ES conformance
test ES2-CTS.gtf.GL2Tests.glGetUniform.glGetUniform.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Christoph Brill <egore911@gmail.com>