libgit2: Always use the bundled PCRE library. (JuliaLang#56129)

This is how Yggdrasil builds the library.

Author: maleadt

deps/libgit2.mk

@@ -42,6 +42,10 @@ ifneq (,$(findstring $(OS),Linux FreeBSD OpenBSD))
 LIBGIT2_OPTS += -DUSE_HTTPS="mbedTLS" -DUSE_SHA1="CollisionDetection" -DCMAKE_INSTALL_RPATH="\$$ORIGIN"
 endif
 
+# use the bundled distribution of libpcre. we should consider linking against the
+# pcre2 library we're building anyway, but this is currently how Yggdrasil does it.
+LIBGIT2_OPTS += -DREGEX_BACKEND="builtin"
+
 LIBGIT2_SRC_PATH := $(SRCCACHE)/$(LIBGIT2_SRC_DIR)
 
 $(BUILDDIR)/$(LIBGIT2_SRC_DIR)/build-configured: $(LIBGIT2_SRC_PATH)/source-extracted