TextureResize calls strlen(NULL) when no GL context is current

[d4rken]

Emulator 37.3.1 (build 16373887), Linux x86_64, RTX 4090 / NVIDIA 595.91.07, -gpu host, API 36 google_apis x86_64. The emulator segfaults a few minutes into use, windowed or -no-window. Four cores, same stack:

#0 __strlen_avx2 (libc.so.6)
#1 libgfxstream_backend.so+0x55bc08  TextureResize::TextureResize(unsigned, unsigned)

The last log line is gles_v2_imp.cpp:glGetString:2882 error null ctx. ColorBufferGl::create builds a TextureResize, whose constructor passes glGetString(GL_EXTENSIONS) to HasExtension without a null check (host/gl/texture_resize.cpp), so a color buffer created with no current context becomes strlen(NULL). I don't know why the context is missing. -gpu swangle_indirect doesn't crash.

[jmacnak]

(Potentially related to b/561516389 @bohu-google )