examples/gl/gpuParticleSystemExample ofShader: setupShaderFromSource(): GL_GEOMETRY_SHADER_EXT shader failed to compile

lspci
00:02.0 VGA compatible controller: Intel Corporation Skylake GT2 [HD Graphics 520] (rev 07)
uname -a
Linux bb7 5.4.0-58-generic #64-Ubuntu SMP Wed Dec 9 08:16:25 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

juser@bb7:~/Downloads/of_v20201224_linux64gcc6_release/examples/gl/gpuParticleSystemExample$ DISPLAY=:0 make RunRelease 
[ error ] ofShader: setupShaderFromSource(): GL_GEOMETRY_SHADER_EXT shader failed to compile
[ error ] ofShader: GL_GEOMETRY_SHADER_EXT shader reports:
0:2(12): warning: extension `GL_EXT_geometry_shader4' unsupported in geometry shader
0:14(21): error: `gl_VerticesIn' undeclared
0:14(17): error: operands to relational operators must be scalar and numeric
0:14(17): error: loop condition must be scalar boolean
0:15(49): error: `gl_PositionIn' undeclared
0:15(49): error: operands to arithmetic operators must be numeric
0:15(16): error: operands to arithmetic operators must be numeric
0:20(48): error: `gl_PositionIn' undeclared
0:20(48): error: operands to arithmetic operators must be numeric
0:20(16): error: operands to arithmetic operators must be numeric
0:25(48): error: `gl_PositionIn' undeclared
0:25(48): error: operands to arithmetic operators must be numeric
0:25(16): error: operands to arithmetic operators must be numeric
0:31(48): error: `gl_PositionIn' undeclared
0:31(48): error: operands to arithmetic operators must be numeric
0:31(16): error: operands to arithmetic operators must be numeric
0:36(48): error: `gl_PositionIn' undeclared
0:36(48): error: operands to arithmetic operators must be numeric
0:36(16): error: operands to arithmetic operators must be numeric
0:41(48): error: `gl_PositionIn' undeclared
0:41(48): error: operands to arithmetic operators must be numeric
0:41(16): error: operands to arithmetic operators must be numeric

[ error ] ofShader: GL_GEOMETRY_SHADER_EXT, offending line 12 :
	   10	    // For each vertex moved to the right position on the vertex shader
	   11	    // it makes 6 more vertex that makes 2 GL_TRIANGLE_STRIP
	   12	    // that´s going to be the frame for the pixels of the sparkImg texture
	   13	    //
	   14	    for(int i = 0; i < gl_VerticesIn; i++){

[ error ] ofShader: checkProgramLinkStatus(): program failed to link
[ error ] ofShader: ofShader: program reports:
error: linking with uncompiled/unspecialized shader

I see a window, black background, light blue square at 0,0 and the fps: 60.0xxx giggling about.

Start by running the reported RunRelease command in examples/gl/gpuParticleSystemExample on the Intel/Linux setup and inspect the example's geometry shader source. Confirm how the shader compilation failure occurs and define done as the example compiling and running without the reported geometry-shader and program-link errors.