community/ocaml-lablgtk: fix build by disabling -fno-common

Currently no patch for it:

/usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gdk.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtk.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkbin.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkbroken.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkbutton.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkassistant.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkedit.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtklist.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkmenu.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkmisc.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkpack.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkrange.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtkstock.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtktext.o:(.bss+0x0): multiple definition of ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here /usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ml_gtktree.o:(.bss+0x0): multiple definition of `ml_table_extension_events'; ml_gdkpixbuf.o:(.bss+0x0): first defined here