GLES: fix ofPolyline / ofBeginShape outlines not drawing (iOS, WebGL) and ignoring line width (Android)

[danoli3]

Problem

On OpenGL ES, open outlines don't draw: ofPolyline::draw(), and ofNoFill() + ofBeginShape() / ofEndShape(). The waveforms in audioOutputExample on WebGL are one visible case.

draw(ofPolyline) had an ES-only path that binds the positions as a client array and draws a raw GL_LINE_STRIP / GL_LINE_LOOP. With the lines shaders enabled (the default since #8019), setAttributes() selects the lines shader. That shader expects the triangle mesh draw(ofMesh) builds from the line, with prev/next vertex attributes, so the raw strip:

• iOS (ES 3.0 and 2.0) and WebGL (1 and 2): draws nothing.
• Android: draws garbled, wavy lines and ignores ofSetLineWidth.

#8533 removed the !TARGET_EMSCRIPTEN exclusion from that path, which is when WebGL broke.

Change

draw(ofPolyline) on ES uses the client-array path only when the lines shaders are disabled. Otherwise it uses the same VBO mesh path as desktop GL, which goes through draw(ofMesh) and its lines-shader bundle.

Tested

The same test on each platform draws eight outline cases over black and counts the drawn pixels in each band:

1. open ofBeginShape, width 1
2. open ofBeginShape, width 3
3. ofDrawLine, width 1
4. ofDrawLine, width 3
5. ofPolyline::draw, width 1
6. ofPolyline::draw, width 3
7. unfilled rectangle
8. closed ofBeginShape

Platform	master	this PR
WebGL2 / WebGL1 (Chrome)	open ofBeginShape and ofPolyline blank, closed shape skewed	✅ all 8
iOS simulator, ES 3.0 and ES 2.0	open ofBeginShape, ofPolyline and closed shape blank	✅ all 8
Android 14 emulator, ES 3.0	lines garbled, width 3 drawn at 1 px	✅ all 8, correct widths

ofDrawLine and the unfilled rectangle already worked on master and are unchanged.

WebGL2: master / this PR

iOS simulator, ES 3.0: master / this PR

Android emulator, ES 3.0: master / this PR

Not tested on real devices.