libcap: avoid %optflags macro

[bcressey]

Issue number:
Related: bottlerocket-os/bottlerocket-sdk#244

Description of changes:
%optflags is the result of augmenting %__global_compiler_flags with arch-specific flags. These may not work when cross-compiling as the target arch may not match the host arch.

Switch to the baseline %__global_compiler_flags instead. These flags are only relevant when compiling software for the host, which should not be included in the final set of packaged artifacts, so any missed optimizations are not a concern.

Testing done:
Before this change, cross-compiling for x86_64 on an aarch64 build host fails with this error:

  0.306 gcc -O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Wno-complain-wrong-lang -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -m64 -march=x86-64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -mtls-dialect=gnu2 -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -Dlinux -Wall -Wwrite-strings -Wpointer-arith -Wcast-qual -Wcast-align -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline -Wshadow -Wunreachable-code  -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I/home/builder/rpmbuild/BUILD/bottlerocket-libcap-2.70-build/libcap-2.70/libcap/../libcap/include/uapi -I/home/builder/rpmbuild/BUILD/bottlerocket-libcap-2.70-build/libcap-2.70/libcap/../libcap/include _makenames.c -o _makenames
  0.308 gcc: error: unrecognized argument in option ‘-mtls-dialect=gnu2’
  0.308 gcc: note: valid arguments to ‘-mtls-dialect=’ are: desc trad
  0.309 make[1]: *** [Makefile:79: _makenames] Error 1

After, the build succeeds.

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.