CPU feature checking - require SSE3

 The packages in the isa-support family probe for microprocessor Instruction
 Set Architecture features such as SSE3. By refusing to install on machines
 lacking a required feature, they allow ISA requirements to be handled in
 terms of package dependencies.
 .
 This is a mostly dummy package which checks for SSE3 and refuses to install
 on unsupported hardware.
 .
 Streaming SIMD Extensions (SSE) is a single instruction, multiple data
 (SIMD) instruction set extension.
 .
 SSE3, also called PNI (Prescott New Instructions), is an incremental upgrade
 to SSE2, adding a handful of new operations useful for processing media. It
 is available on almost any 64-bit-capable processor except for some early
 AMD models (Sledgehammer and Clawhammer), but is not available on most
 32-bit-only hardware.