cmake: avoid unnecessary `-L` for implicit link dirs

The unnecessary `-L` may unexpectedly change the toolchain's chosen
search order in implicit link directories.

Causing this error noticed by a vcpkg user, and reproduced, in the
context of Android NDK r22b, API level 16, static library and CRT
linkage:
~~~
configure:23635: checking whether libcurl is usable
configure:23669: armv7a-linux-androideabi16-clang -o conftest
  --sysroot=/home/runner/work/boinc/boinc/3rdParty/android/android-ndk-r22b/toolchains/llvm/prebuilt/linux-x86_64/sysroot
  -DANDROID -DDECLARE_TIMEZONE -Wall
  -I/home/runner/work/boinc/boinc/3rdParty/buildCache/android/android-tc/arm/arm-linux-androideabi/include
  -O3 -fomit-frame-pointer -fPIE -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -D__ANDROID_API__=16 -Wall
  -I/home/runner/work/boinc/boinc/3rdParty/android/vcpkg/installed/arm-android/include
  -I/home/runner/work/boinc/boinc/3rdParty/android/vcpkg/installed/arm-android/lib/pkgconfig/../../include -DCURL_STATICLIB
  -L/home/runner/work/boinc/boinc/3rdParty/android/vcpkg/installed/arm-android/lib -llog -fPIE -pie -latomic -static-libstdc++
  -march=armv7-a -Wl,--fix-cortex-a8 -L/home/runner/work/boinc/boinc/3rdParty/android/vcpkg/installed/arm-android/lib conftest.c
  -L/home/runner/work/boinc/boinc/3rdParty/android/vcpkg/installed/arm-android/lib/pkgconfig/../../lib -lcurl
  -L/home/runner/work/boinc/boinc/3rdParty/android/android-ndk-r22b/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/arm-linux-androideabi
  -lssl -lcrypto -ldl -pthread -lz  >&5
clang: warning: argument unused during compilation: '-static-libstdc++' [-Wunused-command-line-argument]
ld: error: undefined symbol: bsd_signal
>>> referenced by legacy_signal_inlines.h:116 (/home/runner/work/boinc/boinc/3rdParty/android/android-ndk-r22b/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/include/android/legacy_signal_inlines.h:116)
>>>               libcrypto-lib-ui_openssl.o:(read_string_inner) in archive /home/runner/work/boinc/boinc/3rdParty/android/vcpkg/installed/arm-android/lib/libcrypto.a
ld: error: undefined symbol: pthread_atfork
~~~
with the unnecessary option
~~~
-L/home/runner/work/boinc/boinc/3rdParty/android/android-ndk-r22b/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/arm-linux-androideabi
~~~
Reference: https://github.com/microsoft/vcpkg/pull/43463#issuecomment-2638611717

Closes #16233
1 file changed
tree: 68e0b2f89e54ded46e7f1ff7a5b2539d107938e6
  1. .circleci/
  2. .github/
  3. CMake/
  4. docs/
  5. include/
  6. lib/
  7. LICENSES/
  8. m4/
  9. packages/
  10. plan9/
  11. projects/
  12. scripts/
  13. src/
  14. tests/
  15. winbuild/
  16. .dir-locals.el
  17. .git-blame-ignore-revs
  18. .gitattributes
  19. .gitignore
  20. .mailmap
  21. acinclude.m4
  22. appveyor.sh
  23. appveyor.yml
  24. buildconf
  25. CHANGES.md
  26. CMakeLists.txt
  27. configure.ac
  28. COPYING
  29. curl-config.in
  30. Dockerfile
  31. GIT-INFO.md
  32. libcurl.pc.in
  33. Makefile.am
  34. README
  35. README.md
  36. RELEASE-NOTES
  37. renovate.json
  38. REUSE.toml
  39. SECURITY.md
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