bug: glslc -E does not escape newlines in string literals

[Mozartenhimer]

Pretty straight forward to explain. preprocessing with glslc -E does not escape newlines in string literals when re-printing the string literal. This results in string literals breaking the source if they're used.

Minimal reproducible example:

~> cat shader.glsl                                                                                                                                                       
#version 450
#extension GL_EXT_debug_printf : enable

int main(){
        debugPrintf("with Newline\n");
}

~> glslc -E shader.glsl                                                                                          
#version 450
#extension GL_EXT_debug_printf : enable

int main() {
 debugPrintf("with Newline
");
}

                                                                                                              

~> glslc --version                                                                                               
shaderc v2023.8 v2025.3
spirv-tools v2025.3 v2022.4-833-g33e02568
glslang 11.1.0-1253-gefd24d75

Target: SPIR-V 1.0