https://buildd.debian.org/status/logs.php?pkg=gulkan&ver=0.15.1-2.3%2Bb2

...
FAILED: [code=1] examples/external-memory
cc  -o examples/external-memory examples/external-memory.p/meson-generated_.._.._res_test_resources.c.o examples/external-memory.p/meson-generated_.._.._shaders_shader_resources.c.o examples/external-memory.p/external-memory.c.o -Wl,--as-needed -Wl,--no-undefined -Wl,--whole-archive -Wl,--start-group examples/common/libcommon.a -Wl,--no-whole-archive -Wl,-z,relro -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/build/reproducible-path/gulkan-0.15.1=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2 '-Wl,-rpath,$ORIGIN/../src' src/libgulkan-0.15.so.0.15.1 /usr/lib/x86_64-linux-gnu/libcairo.so /usr/lib/x86_64-linux-gnu/libgio-2.0.so /usr/lib/x86_64-linux-gnu/libgobject-2.0.so /usr/lib/x86_64-linux-gnu/libglib-2.0.so /usr/lib/x86_64-linux-gnu/libgdk_pixbuf-2.0.so /usr/lib/x86_64-linux-gnu/libvulkan.so /usr/lib/x86_64-linux-gnu/libgraphene-1.0.so /usr/lib/x86_64-linux-gnu/libglfw.so /usr/lib/x86_64-linux-gnu/libGLEW.so /usr/lib/x86_64-linux-gnu/libGLU.so -Wl,--end-group
/usr/bin/x86_64-linux-gnu-ld.bfd: examples/external-memory.p/external-memory.c.o: in function `gl_check_error':
./obj-x86_64-linux-gnu/../examples/external-memory.c:86:(.text+0xd1): undefined reference to `glGetError'
/usr/bin/x86_64-linux-gnu-ld.bfd: ./obj-x86_64-linux-gnu/../examples/external-memory.c:86:(.text+0x122): undefined reference to `glGetError'
/usr/bin/x86_64-linux-gnu-ld.bfd: examples/external-memory.p/external-memory.c.o: in function `_init_texture':
./obj-x86_64-linux-gnu/../examples/external-memory.c:150:(.text+0x340): undefined reference to `glGenTextures'
/usr/bin/x86_64-linux-gnu-ld.bfd: ./obj-x86_64-linux-gnu/../examples/external-memory.c:151:(.text+0x34d): undefined reference to `glBindTexture'
/usr/bin/x86_64-linux-gnu-ld.bfd: ./obj-x86_64-linux-gnu/../examples/external-memory.c:154:(.text+0x36d): undefined reference to `glTexParameteri'
/usr/bin/x86_64-linux-gnu-ld.bfd: ./obj-x86_64-linux-gnu/../examples/external-memory.c:156:(.text+0x38d): undefined reference to `glTexParameteri'
/usr/bin/x86_64-linux-gnu-ld.bfd: ./obj-x86_64-linux-gnu/../examples/external-memory.c:158:(.text+0x3ad): undefined reference to `glTexParameteri'
/usr/bin/x86_64-linux-gnu-ld.bfd: ./obj-x86_64-linux-gnu/../examples/external-memory.c:168:(.text+0x416): undefined reference to `glTexSubImage2D'
/usr/bin/x86_64-linux-gnu-ld.bfd: ./obj-x86_64-linux-gnu/../examples/external-memory.c:173:(.text+0x42b): undefined reference to `glFinish'
/usr/bin/x86_64-linux-gnu-ld.bfd: examples/external-memory.p/external-memory.c.o: in function `_finalize':
./obj-x86_64-linux-gnu/../examples/external-memory.c:55:(.text+0x4e2): undefined reference to `glDeleteTextures'
collect2: error: ld returned 1 exit status
...

Root cause: GLEW 2.3.1 (glew_2.3.1+dfsg2-5) changed ${GLEW_LIBRARIES}
linkage from PUBLIC to PRIVATE in its CMakeLists.txt (Debian patch
0005-CMakeLists.txt-fix-linking.patch, commit dcd1d56). Previously libGL
propagated transitively to any consumer of the GLEW pkg-config target;
now it does not, so gulkan's external-memory example and test_texture_external
test both fail to link with undefined references to glGetError, glGenTextures,
glBindTexture, glTexParameteri, glTexSubImage2D, glFinish, glDeleteTextures.

Fix: add gl_dep = dependency('gl', required: false) to the root meson.build
and pass it explicitly to the two affected GLEW-dependent targets.

Thanks & Regards,
Azeez Syed