Fix HoughLinesP to handle edge cases and prevent panics (#51) #220

Job	Run time
Build Khronos OpenVX sample	1m 18s
build	1m 46s
Build rustVX (main)	0s
baseline	12s
KHR extension: user-data-object	7s
image-ops	13s
KHR extension: pipelining stress	38s
data-objects	8s
graph	8s
Enhanced-Vision: Post-Processing	14s
vision-features	17s
Enhanced-Vision: Feature Extraction	13s
Enhanced-Vision: Tensor Transforms	8s
vision-pyramid	13s
KHR extension: pipelining fast	8s
vision-filters	55s
vision-color	16s
Enhanced-Vision: Control Flow	8s
Enhanced-Vision: Advanced Filtering	1m 4s
vision-arithmetic	24s
vision-statistics	9s
vision-geometric	37s
Enhanced-Vision: Tensor Arithmetic	11s
Perf gate (PR vs main)	0s
Benchmark & compare (rustVX vs Khronos sample)	5m 48s
	15m 15s

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