cad/alliance: Unbreak build with GCC 10 (-fno-common default)

/usr/local/bin/ld: /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_desc_y.o):(.bss+0x24): multiple definition of `pat_decl_y_errflag'; /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_decl_y.o):(.bss+0x20): first defined here
/usr/local/bin/ld: /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_desc_y.o):(.bss+0x10): multiple definition of `pat_decl_y_val'; /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_decl_y.o):(.bss+0x10): first defined here
/usr/local/bin/ld: /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_desc_y.o):(.bss+0x0): multiple definition of `pat_decl_y_lval'; /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_decl_y.o):(.bss+0x0): first defined here
/usr/local/bin/ld: /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_desc_y.o):(.bss+0x2c): multiple definition of `pat_decl_y_debug'; /wrkdirs/usr/ports/cad/alliance/work/alliance/src/pat/src/.libs/libPat.a(pat_decl_y.o):(.bss+0x24): first defined here

http://package18.nyi.freebsd.org/data/121amd64-default-PR244494/2020-06-10_18h04m44s/logs/errors/alliance-5.1.1_1.log

Also USES=compiler:c++0x & USE_GCC=any can be reduced to USE_GCC=yes

PR: 246700