contrib: Do not pass debug/optim flags to meson

This fixes the meson underscore prefix test, which misbehaves
when -g is passed, as it would detect the debug string without
underscore first and incorrectly report that no underscore
prefix for symbols is used.

Fixes build issues with dav1d, which relies on the underscore
prefix check.

See: https://github.com/mesonbuild/meson/issues/5482


Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>
(cherry picked from commit 3426d7bc)
Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>

contrib/src/main.mak

@@ -165,16 +165,14 @@ cppcheck = $(shell $(CC) $(CFLAGS) -E -dM - < /dev/null | grep -E $(1))
 
 EXTRA_CFLAGS += -I$(PREFIX)/include
 CPPFLAGS := $(CPPFLAGS) $(EXTRA_CFLAGS)
-CFLAGS := $(CFLAGS) $(EXTRA_CFLAGS) -g
-CXXFLAGS := $(CXXFLAGS) $(EXTRA_CFLAGS) $(EXTRA_CXXFLAGS) -g
+CFLAGS := $(CFLAGS) $(EXTRA_CFLAGS)
+CXXFLAGS := $(CXXFLAGS) $(EXTRA_CFLAGS) $(EXTRA_CXXFLAGS)
 LDFLAGS := $(LDFLAGS) -L$(PREFIX)/lib $(EXTRA_LDFLAGS)
 
 ifndef WITH_OPTIMIZATION
-CFLAGS := $(CFLAGS) -O0
-CXXFLAGS := $(CXXFLAGS) -O0
+DBGOPTIMFLAGS = -g -O0
 else
-CFLAGS := $(CFLAGS) -O2
-CXXFLAGS := $(CXXFLAGS) -O2
+DBGOPTIMFLAGS = -g -O2
 endif
 
 # Do not export those! Use HOSTVARS.
@@ -291,18 +289,26 @@ HOSTTOOLS := \
 	PATH="$(PREFIX)/bin:$(PATH)"
 HOSTVARS := \
 	CPPFLAGS="$(CPPFLAGS)" \
-	CFLAGS="$(CFLAGS)" \
-	CXXFLAGS="$(CXXFLAGS)" \
+	CFLAGS="$(CFLAGS) $(DBGOPTIMFLAGS)" \
+	CXXFLAGS="$(CXXFLAGS) $(DBGOPTIMFLAGS)" \
 	LDFLAGS="$(LDFLAGS)"
 HOSTVARS_PIC := $(HOSTTOOLS) \
 	CPPFLAGS="$(CPPFLAGS) $(PIC)" \
-	CFLAGS="$(CFLAGS) $(PIC)" \
-	CXXFLAGS="$(CXXFLAGS) $(PIC)" \
+	CFLAGS="$(CFLAGS) $(DBGOPTIMFLAGS) $(PIC)" \
+	CXXFLAGS="$(CXXFLAGS) $(DBGOPTIMFLAGS) $(PIC)" \
 	LDFLAGS="$(LDFLAGS)"
 
 # Keep a version of HOSTVARS without the tools, since meson requires the
 # tools variables to point to the native ones
-HOSTVARS_MESON := $(HOSTVARS)
+ifdef HAVE_CROSS_COMPILE
+HOSTVARS_MESON := PATH="$(PREFIX)/bin:$(PATH)"
+else
+HOSTVARS_MESON := $(HOSTTOOLS) \
+	CPPFLAGS="$(CPPFLAGS)" \
+	CFLAGS="$(CFLAGS)" \
+	CXXFLAGS="$(CXXFLAGS)" \
+	LDFLAGS="$(LDFLAGS)"
+endif
 HOSTVARS := $(HOSTTOOLS) $(HOSTVARS)
 
 download_git = \